Rewrite section pages so that all the content is written in markdown

[colinkiama]

Currently, section pages content is all written in the pages which is causes issues with translations.

Here's what needs to happen:

• Macros that are part of the page content need to be replaced with shortcodes
• All the section page content will be removed from the template pages and added to their respective _index.md pages
• Update the translated markdown content pages for the section pages to include all of the page content.
• Update contributor guide if needed, to explain the new changes
• Ensure that shortcodes only use translations for info specific to shortcode e.g toggle button label, tooltip etc
• When this issue is completed, create translation request issues for each language that the site has translations for so far

With these changes, we should have much better translation coverage across the site