add check-metadata in doc

README.md

@@ -128,6 +128,8 @@ For each command, the option `-h` give u some help.
  `./manage.py make-widgets` to make a file that groups all jinja2 widgets macros for easier includes. It is automatically called by `runserver` and `distill-local` commands. \
  See an example in `EXAMPLE.md`
 
+ `./manage.py check-metadata` to check if metadata specified in `JFME_CONTENT_REQUIRED_METADATA` are set in pages.
+
 ## Others
 
 JFM-Engine is a friendly fork of [JSSG](https://github.com/jtremesay/jssg/) made in agreement with the JSSG developer because of different goals. \

content/templates/jinja2/allwidgets.html

@@ -19,7 +19,7 @@
     <div class="navbar__container__right">
       <a class="btn btn-sm btn-primary" href="{{ CTA_URL }}"
          target="{{ CTA_TARGET }}">{{ CTA_LABEL }}</a>
-      <a href="{{ url('page', args=[CHANGE_LANG_URL]) }}">
+      <a href="{{ url_for_slug_path(CHANGE_LANG_URL) }}">
         <img class="languageFlag" src="{{ static(CHANGE_LANG_FLAG_URL)}}" alt="{{ CHANGE_LANG_ALT }}"/>
       </a>
     </div>