Merge pull request #442 from blueyed/doc

Minor doc fixes

doc/airline.txt

@@ -623,7 +623,7 @@ to your liking.  Here is an example: >
     return 1
   endfunction
 <
-The above example uses various some example highlight groups to demonstrate
+The above example uses various example highlight groups to demonstrate
 that you can use any combination from the loaded colorscheme. However, if
 you want colors to change between modes, you should use one of the section
 highlight groups, e.g. `airline_a` and `airline_b`.