docs: update readme with instructions and examples on use

Author: GROOOOAAAARK

README.md

@@ -17,3 +17,33 @@ zig build run
 ```bash
 ./zig-out/bin/zig-commit-emoji --help
 ```
+
+## Features
+
+### List
+
+#### What does it do ?
+
+Will simply list all emojis available with their description.
+
+#### How to use ?
+
+```bash
+./zig-commit-emoji list
+```
+
+### Search
+
+#### What does it do ?
+
+Will look for the keyword typed in all emojis descriptions.
+
+#### How to use ?
+
+```bash
+./zig-commit-emoji search -k <keyword>
+```
+
+```bash
+./zig-commit-emoji search -k "feat"
+```