tpl/tplimpl: Update details shortcode

- Remove localization of default summary value
- Add title attribute
- Reformat to be consistent with other embedded templates
- Simplify and improve integration test
- Update documentation

content/en/content-management/shortcodes.md

@@ -101,32 +101,42 @@ Although you can call this shortcode using the `{{</* */>}}` notation, computati
 {{% note %}}
 To override Hugo's embedded `details` shortcode, copy the [source code] to a file with the same name in the layouts/shortcodes directory.
 
-This may be useful if you are wanting access to more global HTML attributes. 
-
 [source code]: {{% eturl details %}}
 {{% /note %}}
 
-Use the `details` shortcode to generate a collapsible details HTML element. For example:
+Use the `details` shortcode to create a `details` HTML element. For example:
 
 ```text
-{{</* details summary="Custom Summary Text" */>}}
-Showing custom `summary` text.
+{{</* details summary="See the details" */>}}
+This is a **bold** word.
 {{</* /details */>}}
 ```
 
-Additional examples can be found in the source code. The `details` shortcode can use the following named arguments:
+Hugo renders this to:
+
+```html
+<details>
+  <summary>See the details</summary>
+  <p>This is a <strong>bold</strong> word.</p>
+</details>
+```
+
+The details shortcode accepts these named arguments:
 
 summary
-: (`string`) Optional. Specifies the content of the child summary element. Default is "Details"
+: (`string`) The content of the child `summary` element rendered from Markdown to HTML. Default is `Details`.
 
 open
-: (`bool`) Optional. Whether to initially display the contents of the details element. Default is `false`.
+: (`bool`) Whether to initially display the content of the `details` element. Default is `false`.
+
+class
+: (`string`) The value of the element's `class` attribute.
 
 name
-: (`string`) Optional. The value of the element's name attribute.
+: (`string`) The value of the element's `name` attribute.
 
-class
-: (`string`) Optional. The value of the element's class attribute.
+title
+: (`string`) The value of the element's `title` attribute.
 
 ### figure