Umbraco 15.3 release documentation updates

[AndyButland]

Description

Documentation updates related to the 15.3 release:

• Added details of additional option for publish with descendants - see Split force for publish descendants into separate options for publish unpublish and re-publish unedited (15)  Umbraco-CMS#18270
• Added details of unroutable content warnings configuration - see V15: Warn when content is unroutable Umbraco-CMS#17837

Note that some updates have been included in this PR (where they were merged up from 13.7): #6830

Type of suggestion

• Typo/grammar fix
• Updated outdated content
• New content
• Updates related to a new version
• Other

Product & version (if relevant)

Umbraco 15.3

Deadline (if relevant)

Can go live any time from today.

[AndyButland]

This is ready for review and publication now. The RC is released so it's fine to go live at any time from today.

[sofietoft]

Just a thought:
I can see your changing the headings, but adding correct spacing.
This should be consistent across all configuration articles - so I'm just wondering which we're going with.
The reason we kept them without the spaces, was to increase searchability 🤔 as without the spaces is the "correct" formatting if you look at the config files, right?

[AndyButland]

Thanks @sofietoft - I only did this really to make it consistent within the article; I didn't look wider than that. As you say, maybe using the literal configuration key is best for searchability. Happy to align on that across the configuration articles if you or one of your team wants to to that - or also I can do it myself next week. Just let me know what you'd prefer.

[sofietoft]

Sounds great!
I'll add a task for the docs team.
I don't think it's an urgent thing - so we'll get to it when we get to it!
Thanks for sharing your thoughts on this 💪