runes concept: make strings, runes and bytes explanation clearer (#2824)

* Clarify relationship of Strings and Runes

As discussed in [the forums], this patch makes the changes desired to
clarify how Strings are related to Runes and hopefully clears up some
confusing and potentially misleading statements.

Ref: #2768

[the forums]: https://forum.exercism.org/t/potential-misleading-information-on-the-golang-runes-chapter/10082/1

* Introduction for exercise updated

This is currently identical to the concepts/runes/introduction.md file.

concepts/runes/about.md

@@ -83,12 +83,13 @@ fmt.Printf("myRune Unicode character: %c\n", myRune)
 ## Runes and Strings
 
 Strings in Go are encoded using UTF-8 which means they contain Unicode characters.
-Since the `rune` type represents a Unicode character, a string in Go is often referred to as a sequence of runes.
-However, runes are stored as 1, 2, 3, or 4 bytes depending on the character.
-Due to this, strings are really just a sequence of bytes.
-In Go, slices are used to represent sequences and these slices can be iterated over using `range`.
+Characters in strings are stored and encoded as 1, 2, 3, or 4 bytes depending on the Unicode character they represent.
+
+In Go, slices are used to represent sequences and these slices can be iterated over using range.
+When we iterate over a string, Go converts the string into a series of Runes, each of which is 4 bytes (remember, the rune type is an alias for an `int32`!)
 
 Even though a string is just a slice of bytes, the `range` keyword iterates over a string's runes, not its bytes.
+
 In this example, the `index` variable represents the starting index of the current rune's byte sequence and the `char` variable represents the current rune:
 
 ```go

concepts/runes/introduction.md

@@ -74,12 +74,13 @@ fmt.Printf("myRune Unicode code point: %U\n", myRune)
 ## Runes and Strings
 
 Strings in Go are encoded using UTF-8 which means they contain Unicode characters.
-Since the `rune` type represents a Unicode character, a string in Go is often referred to as a sequence of runes.
-However, runes are stored as 1, 2, 3, or 4 bytes depending on the character.
-Due to this, strings are really just a sequence of bytes.
-In Go, slices are used to represent sequences and these slices can be iterated over using `range`.
+Characters in strings are stored and encoded as 1, 2, 3, or 4 bytes depending on the Unicode character they represent.
+
+In Go, slices are used to represent sequences and these slices can be iterated over using range.
+When we iterate over a string, Go converts the string into a series of Runes, each of which is 4 bytes (remember, the rune type is an alias for an `int32`!)
 
 Even though a string is just a slice of bytes, the `range` keyword iterates over a string's runes, not its bytes.
+
 In this example, the `index` variable represents the starting index of the current rune's byte sequence and the `char` variable represents the current rune:
 
 ```go

exercises/concept/logs-logs-logs/.docs/introduction.md

@@ -1,10 +1,14 @@
 # Introduction
 
-The `rune` type in Go is an alias for `int32`. Given this underlying `int32` type, the `rune` type holds a signed 32-bit integer value. However, unlike an `int32` type, the integer value stored in a `rune` type represents a single Unicode character.
+The `rune` type in Go is an alias for `int32`.
+Given this underlying `int32` type, the `rune` type holds a signed 32-bit integer value.
+However, unlike an `int32` type, the integer value stored in a `rune` type represents a single Unicode character.
 
 ## Unicode and Unicode Code Points
 
-Unicode is a superset of ASCII that represents characters by assigning a unique number to every character. This unique number is called a Unicode code point. Unicode aims to represent all the world's characters including various alphabets, numbers, symbols, and even emoji as Unicode code points.
+Unicode is a superset of ASCII that represents characters by assigning a unique number to every character.
+This unique number is called a Unicode code point.
+Unicode aims to represent all the world's characters including various alphabets, numbers, symbols, and even emoji as Unicode code points.
 
 In Go, the `rune` type represents a single Unicode code point.
 
@@ -21,7 +25,9 @@ The following table contains example Unicode characters along with their Unicode
 
 ## UTF-8
 
-UTF-8 is a variable-width character encoding that is used to encode every Unicode code point as 1, 2, 3, or 4 bytes. Since a Unicode code point can be encoded as a maximum of 4 bytes, the `rune` type needs to be able to hold up to 4 bytes of data. That is why the `rune` type is an alias for `int32` as an `int32` type is capable of holding up to 4 bytes of data.
+UTF-8 is a variable-width character encoding that is used to encode every Unicode code point as 1, 2, 3, or 4 bytes.
+Since a Unicode code point can be encoded as a maximum of 4 bytes, the `rune` type needs to be able to hold up to 4 bytes of data.
+That is why the `rune` type is an alias for `int32` as an `int32` type is capable of holding up to 4 bytes of data.
 
 Go source code files are encoded using UTF-8.
 
@@ -67,9 +73,15 @@ fmt.Printf("myRune Unicode code point: %U\n", myRune)
 
 ## Runes and Strings
 
-Strings in Go are encoded using UTF-8 which means they contain Unicode characters. Since the `rune` type represents a Unicode character, a string in Go is often referred to as a sequence of runes. However, runes are stored as 1, 2, 3, or 4 bytes depending on the character. Due to this, strings are really just a sequence of bytes. In Go, slices are used to represent sequences and these slices can be iterated over using `range`.
+Strings in Go are encoded using UTF-8 which means they contain Unicode characters.
+Characters in strings are stored and encoded as 1, 2, 3, or 4 bytes depending on the Unicode character they represent.
 
-Even though a string is just a slice of bytes, the `range` keyword iterates over a string's runes, not its bytes. In this example, the `index` variable represents the starting index of the current rune's byte sequence and the `char` variable represents the current rune:
+In Go, slices are used to represent sequences and these slices can be iterated over using range.
+When we iterate over a string, Go converts the string into a series of Runes, each of which is 4 bytes (remember, the rune type is an alias for an `int32`!)
+
+Even though a string is just a slice of bytes, the `range` keyword iterates over a string's runes, not its bytes.
+
+In this example, the `index` variable represents the starting index of the current rune's byte sequence and the `char` variable represents the current rune:
 
 ```go
 myString := "❗hello"
@@ -85,7 +97,8 @@ for index, char := range myString {
 // Index: 7	Character: o		Code Point: U+006F
 ```
 
-Since runes can be stored as 1, 2, 3, or 4 bytes, the length of a string may not always equal the number of characters in the string. Use the builtin `len` function to get the length of a string in bytes and the `utf8.RuneCountInString` function to get the number of runes in a string:
+Since runes can be stored as 1, 2, 3, or 4 bytes, the length of a string may not always equal the number of characters in the string.
+Use the builtin `len` function to get the length of a string in bytes and the `utf8.RuneCountInString` function to get the number of runes in a string:
 
 ```go
 import "unicode/utf8"