style: remove trailing whitespace (#12303)

custom/example.zsh

@@ -1,12 +1,12 @@
 # Put files in this folder to add your own custom functionality.
 # See: https://github.com/ohmyzsh/ohmyzsh/wiki/Customization
-# 
+#
 # Files in the custom/ directory will be:
 # - loaded automatically by the init script, in alphabetical order
 # - loaded last, after all built-ins in the lib/ directory, to override them
 # - ignored by git by default
-# 
+#
 # Example: add custom/shortcuts.zsh for shortcuts to your local projects
-# 
+#
 # brainstormr=~/Projects/development/planetargon/brainstormr
 # cd $brainstormr