Update LCS docs for LCS client 15

• Type: New Article
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 6.2.x
• Component/s: Connected Services (LCS)
• Labels: None
• Git Pull Request: https://github.com/sez11a/liferay-docs/pull/1535

Covers LCS client features in the below tickets.

LCS Client 15:
https://issues.liferay.com/browse/CLDSVCS-1695
https://issues.liferay.com/browse/CLDSVCS-1817
https://issues.liferay.com/browse/CLDSVCS-1451

Also includes minor LCS platform updates.