Update LineJoinMode.yaml

[sammygrey]

Added figures from the UIStroke class page, as images are referenced in the table although none exist Changed reference to the "Applying Strokes Article" to reference the UIStroke class page (said article does not exist).

This documentation error was brought to my attention by @XAXA in this devforum post.

Checks

By submitting your pull request for review, you agree to the following:

• This contribution was created in whole or in part by me, and I have the right to submit it under the terms of this repository's open source licenses.
• I understand and agree that this contribution and a record of it are public, maintained indefinitely, and may be redistributed under the terms of this repository's open source licenses.
• To the best of my knowledge, all proposed changes are accurate.

[IgnisRBX]

Hi @sammygrey ,
Thanks for the reminder! I put the images inside each enum value's row instead of above, and corrected the URL link to the article about UI stroke. :)