Missing inline documentation tags and formatting

[huzaifaalmesbah]

Several core files contain inline documentation that does not fully align with WordPress PHP Documentation Standards.
Issues identified:

• Some functions are missing @return tags.
• Full stops (periods) are missing at the end of some function summaries and parameter descriptions.
• Some @param tags are missing descriptions.

Affected files:

• src/bbpress.php
• src/includes/admin/classes/class-bbp-admin.php
• src/includes/forums/functions.php
• src/includes/replies/functions.php
• src/includes/topics/functions.php
• src/includes/users/signups.php

This PR improves the inline documentation coverage and formatting across several core files to align with WordPress PHP Documentation Standards.
## Changes

• Added missing @return tags.
• Fixed missing full stops (periods) in function summaries and descriptions.
• Populated missing @param descriptions.

## Files Modified

• src/includes/admin/classes/class-bbp-admin.php
• src/includes/forums/functions.php
• src/includes/replies/functions.php
• src/includes/topics/functions.php
• src/includes/users/signups.php

See ​#3659

[johnjamesjacoby]

Fixed missing full stops (periods) in function summaries and descriptions.

This is a rule that I've stubbornly avoided working on (because fragments don't deserve full-stops) but I suppose it's time. 😅

[noruzzaman]

I checked the updated files, and everything looks good now.
The missing tags and formatting issues you mentioned earlier are all fixed. Nice work!

[johnjamesjacoby]

In 7380:

Tools - Code Improvement: docs & code formatting improvements.

Props johnjamesjacoby, noruzzaman.

Fixes #3659.

Fixed via ​https://bbpress.trac.wordpress.org/changeset/7380