Document site in introduction

Author: Strokkur424

docs/paper/dev/api/command-api/basics/introduction.mdx

@@ -30,6 +30,7 @@ The following sites are worth-while to look through first when learning about Br
 - [Command Executors](./executors)
 - [Command Registration](./registration)
 - [Command Requirements](./requirements)
+- [Argument Suggestions](./argument-suggestions)
 
 For a reference of more advanced arguments, you should look here:
 - [Minecraft Arguments](../arguments/minecraft)