Add documentation for page creation/import worklfow

If someone tries to simply update a field on a page and save it like this:

page.field = value
page.save()

then it appears to work but only the live page will be updated and the editor will show the last revision that doesn’t have the most recent changes. So if I’m not mistaken this should be the following instead:

page.field = value
page.save_revision().publish()

And we should note that this doesn’t take into account unpublished pages, and published pages with unpublished content.

[lb-]

Some relevant (recent-ish) Stack Overflow questions that relate to this.

https://stackoverflow.com/questions/47788080/how-can-i-create-page-and-set-its-streamfield-value-programmatically

https://stackoverflow.com/questions/47749708/is-there-any-way-to-create-and-publish-pages-by-executing-python-script-in-wagta

https://stackoverflow.com/questions/43040023/programatically-add-a-page-to-a-known-parent

[balazs-endresz]

It’s not ready for a PR but just to give it some structure I’ve created a draft document outlining these issues: https://docs.google.com/document/d/1nd2PugY2g1-Fsw4dHnGrUvMQQuERtvueiu2cO3wulaM/edit

I’ll try to add some concrete examples later on but I’m not really sure about quite a few points there. And I think it would be nice to have this as a separate section in the docs too.