Add dealing with newlines for editor to 5.1-to-6.0

backport of https://github.com/gitlabhq/gitlabhq/commit/2d681c0d1ed14bf23c041aa04fa3e77caceda9a1

doc/update/5.1-to-6.0.md

@@ -89,6 +89,9 @@ sudo -u git -H bundle exec rake cache:clear RAILS_ENV=production
 # Clear and precompile assets
 sudo -u git -H bundle exec rake assets:clean RAILS_ENV=production
 sudo -u git -H bundle exec rake assets:precompile RAILS_ENV=production
+
+#Add dealing with newlines for editor
+sudo -u git -H git config --global core.autocrlf input
 ```
 
 ## 6. Update config files