docs: example command to generate library (#12334)

Author: codermarcos

docs/documentation/generate/library.md

@@ -3,7 +3,7 @@
 # ng generate library
 
 ## Overview
-Generate a library project for Angular.
+`ng generate library [name]` generates a library project for Angular.
 
 ## Alias
 lib - `ng generate lib [name]`