Add Crowdin badge

Author: philwareham

README.md

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 # Textpattern CMS help files
 
+[![Crowdin](https://badges.crowdin.net/textpattern-cms-textpacks/localized.svg)](https://crowdin.com/project/textpattern-cms-textpacks)
+
 This repository contains Inline Help text files (aka 'Pophelp') for [Textpattern CMS](https://textpattern.com).
 
 ## Contributing