docs: tiny style improvements

doc/contributing.rst

@@ -252,6 +252,7 @@ the imperative (command) form. That is, between:
   proc hello*(): string =
     ## Return "hello"
     result = "hello"
+
 or
 
 .. code-block:: nim

doc/manual.rst

@@ -6504,7 +6504,7 @@ alignment requirement of the type are ignored.
 
    type
      sseType = object
-       sseData {.align(16).}: array[4,float32]
+       sseData {.align(16).}: array[4, float32]
 
      # every object will be aligned to 128-byte boundary
      Data = object