Use consistent wording when updating

When the user is asked to update oh-my-zsh it says "[Oh My Zsh] Would
you like to check for updates? [Y/n]:". When the user agreed to update
the next text would say "Upgrading Oh My Zsh" which is inconsistent
with the question.

tools/upgrade.sh

@@ -20,7 +20,7 @@ else
   NORMAL=""
 fi
 
-printf "${BLUE}%s${NORMAL}\n" "Upgrading Oh My Zsh"
+printf "${BLUE}%s${NORMAL}\n" "Updating Oh My Zsh"
 cd "$ZSH"
 if git pull --rebase --stat origin master
 then