Umbraco 15.2 release documentation updates

[AndyButland]

Description

Documentation updates related to the 15.2 releases:

• Added details of content type filters - see Allow for filtering of document type allowed children and allowed at root when creating new content. Umbraco-CMS#18029
• Added alias for new extension condition - see V15: Current User Group Id Condition Umbraco-CMS#18011
• Adds BackOfficeLogo to the ContentSettings - see Explicit endpoints returning the Login and BackOffice logos and background Umbraco-CMS#17696

Type of suggestion

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• Updated outdated content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

Product & version (if relevant)

Umbraco 15.2

Deadline (if relevant)

For publication on Thursday if that's possible please.

[sofietoft]

I've made some edits to the Content Type Filters article to improve the readability a bit.
Please take a look to ensure none of the meaning was lost.

Also, should we remove the "Sending Allowed Children Notification" article from the 15 docs, and redirect to the Content Type Filters article instead?
We could move the note there up a bit, to help people who were looking for the notifications.

[AndyButland]

Looks good to me @sofietoft - just some small suggestion.

And yes agree a redirect would be a good idea here - it is a "like for like" replacement. Thanks if you can set that up.

[sofietoft]

Sounds good @AndyButland !

I can merge this PR now, right?
Then I'll take care of the redirects after.

[AndyButland]

Best to hold for Thursday if that's OK, to align with the release going out.

[sofietoft]

Sure! I'll make sure it's merged tomorrow 💪