Improve copy writing about session and access/refresh tokens lifetimes in the Portal

In the Portal, provide layman's explanation on how to set the session and token lifetimes to achieve what security results

No file, test, or entry point is named. Start by locating the Portal copy about session and access/refresh token lifetimes, then read the surrounding settings and security guidance. Done means the Portal explains in layman's terms how lifetime choices affect security outcomes.

Written by the indexing model from the issue text.