Update docs/syntax_and_semantics/documenting_code.md

Co-authored-by: Julien Portalier <[email protected]>

Author: straight-shoota

docs/syntax_and_semantics/documenting_code.md

@@ -260,7 +260,7 @@ lib FooLib
 end
 ```
 
-If a parent namespace has the `:nodoc:` directive, ahy nested `:showdoc:` directive
+If a parent namespace has the `:nodoc:` directive, any nested `:showdoc:` directive
 has no effect.
 
 ```crystal