This applies to both regular templates and shortcodes. So, if the site language is French and the output format is AMP, this is the (start) of the lookup order for the home page:
1. index.fr.amp.html
2. index.amp.html
3. index.fr.html
4. index.html
5. ...
Fixes#3360
This commit also adds a new command, docshelper, with some utility funcs that adds a JSON datafiles to /docs/data that would be a pain to create and maintain by hand.
Fixes#3242