Add Catalan to the language selector + update README (#1524)

Author: melroy89

README.md

@@ -327,6 +327,7 @@ See [docs.joinmbin.org](https://docs.joinmbin.org)
 Following languages are currently supported/translated:
 
 - Bulgarian
+- Catalan
 - Chinese
 - Danish
 - Dutch

templates/layout/_sidebar.html.twig

@@ -160,7 +160,7 @@
             {% set current = app.request.cookies.get('mbin_lang') ?? header_accept_language ?? kbin_default_lang() %}
             <li>
                 <select data-action="mbin#changeLang">
-                    {% for code in ['bg', 'da', 'de', 'el', 'en', 'eo', 'es', 'fil', 'fr', 'gl', 'it', 'ja', 'nl', 'pl', 'pt', 'pt_BR', 'ru', 'tr', 'uk', 'zh_TW'] %}
+                    {% for code in ['bg', 'ca', 'da', 'de', 'el', 'en', 'eo', 'es', 'fil', 'fr', 'gl', 'it', 'ja', 'nl', 'pl', 'pt', 'pt_BR', 'ru', 'tr', 'uk', 'zh_TW'] %}
                         <option value="{{ code }}" {{ code is same as current ? 'selected' : '' }}>{{ code|language_name(code) }}</option>
                     {% endfor %}
                 </select>