doc: update README

README.md

@@ -1,2 +1,73 @@
-# aix-jetifier
-🚧 WIP
+# Recast
+
+Recast helps make your old extensions compatible with Kodular Creator version 1.5.0 or above.
+
+## Prerequisites
+To use Recast, you need to have Java Runtime Environment (JRE) installed on your system. To check if you have it pre-installed, open your favorite terminal app and run the following:
+```.sh
+java -version
+```
+If you get an output similar to below, JRE is already available on your system.
+```.sh
+java version "1.8.0_281"
+Java(TM) SE Runtime Environment (build 1.8.0_281-b09)
+```
+
+If you don't see an output similar to the above, you will need to install Java before installing Recast.
+
+## Installing
+
+Recast is a command-line tool, and therefore, you first need to install it on your computer to use it. As of now, Recast can be installed on the following operating systems:
+
+* Windows (64 bit)
+* macOS (x86_64 arch)
+* GNU/Linux (x86_64 arch)
+
+### Using PowerShell (Windows)
+1. Open PowerShell.
+2. Copy and paste the following and hit enter:
+    ```.ps1
+    iwr https://raw.githubusercontent.com/shreyashsaitwal/recast/main/scripts/install.ps1 -useb | iex
+    ```
+3. Done! You're all set up.
+
+### Using Shell (macOS and Linux)
+1. Open your favorite shell (terminal).
+2. Copy and paste the following and hit enter:
+    ```.sh
+    curl https://raw.githubusercontent.com/shreyashsaitwal/recast/main/scripts/install.sh -fsSL | sh
+    ```
+3. Once the download is complete, add Recast to your `PATH` by copying the export command from the output (as shown below) and running it:
+4. Done!
+
+## Usage
+To make your old extension compatible with Kodular >1.5.0 using Recast, go through the following steps:
+
+1. Navigate to the directory/folder where your extension is placed.
+2. Open your favorite terminal in that directory.
+3. Now, run the following:
+    ```.sh
+    recast --input you.extension.aix
+    ```
+    (Here, `your.extension.aix` is the name of your extension)
+4. Bingo! A new, recasted extension with the name `your.extension.x.aix` is generated in the current working and ready to be used.
+
+## Tips
+* You can recast multiple extensions all at once by gathering them all in one directory and then running:
+  ```.sh
+  recast --input directory_path
+  ```
+  (Here, `directory_path` is the path to the directory where extensions are stored.)
+
+* If you want to output the recasted extension(s) in a separate directory, all you need to do is specify the `--output` option and pass the path to your desired directory.
+    ```.sh
+    recast --input you.extension.aix --output output_dir_path
+    ```
+    (Here, `output_dir_path` is the path to the output directory.)
+
+## FAQ
+1. Do I need to recast every extension to make it compatible with Kodular >1.5.0?
+**Ans.** No, you don't need to. Only the extensions that started throwing errors after the latest update need to be recasted.
+
+2. Why does Recast print **`No references to support libraries found`** when I try to recast my extension?
+**Ans.** It means that your extension is already compatible with Kodular >1.5.0, and you don't need to recast it.