Update the link to initialize a library in emitters-basics.md (microsoft#2709)

I am following the document to create an emitter and found this link of
steps to initialize a typespec library is not working. So I create this
PR to update the md to point the link to basics.md file, which is for
creating a TypeSpec library.

Author: dinwa-ms

docs/extending-typespec/emitters-basics.md

@@ -9,7 +9,7 @@ TypeSpec emitters are libraries that use various TypeSpec compiler APIs to refle
 
 ## Getting started
 
-TypeSpec emitters are a special kind of TypeSpec library and so have the same getting started instructions. Follow [these steps](#todo) to initialize a typespec library.
+TypeSpec emitters are a special kind of TypeSpec library and so have the same getting started instructions. Follow [these steps](./basics.md) to initialize a typespec library.
 
 ## $onEmit