wp-source WP REST API URL more clear

[juanmaguitar]

Make it more clear the type of URL that need to be set in wp-source

https://test.frontity.org/wp-json/wp/v2/ vs https://test.frontity.org/wp-json/

And some typical examples:

• Wordpress.com
• localhost

etc...

[Poliuk]

In addition to make this more clear in the docs, I think we could also add comments in the different frontity.settings.js files, something like this:

What do you think @juanmaguitar

[mburridge]

One of the things I'd like us to do (not sure if I've mentioned it before) is to extensively comment the mars-theme so that new users can more easily understand what's going on.

We could also do a code tour: https://marketplace.visualstudio.com/items?itemName=vsls-contrib.codetour