- apply general fixes to existing markdown documentation
- various cases of rst syntax still used
- update some links to be the new format
- clean up line breaks (prettier)
Relates to #8383
* Convert the image tag topic to Markdown
* Convert the permissions usage to Markdown
* Convert the topic of snippets to Markdown
* Convert the streamfield topic to markdown
* Convert the writing templates doc to Markdown
As per discussion on https://github.com/wagtail/wagtail/discussions/7732, the changes in the upcoming release (sidebar redesign, removal of hallo.js, module reorganisation) warrant a version bump to 3.0 if we're following semantic versioning.
The "Page models" documentation page in the Wagtail usage guide has
several broken links (see current page at
https://docs.wagtail.io/en/stable/topics/pages.html).
These links work when developing the documentation locally, but not when
served on ReadTheDocs (docs.wagtail.io)
The broken links are all of the form /some/page.html#anchor - somehow
this format doesn't translate properly to get the necessary RTD prefix
(for example /en/stable/).
I've modified these links to use RST references, which will also make
them more robust to future changes.
Documentation examples of `Page.get_context` and `Page.get_template`
lack `*args` and `**kwargs` parameters (which were added way back in
8c4c268641).
This commit adds those missing parameters.
