docs: Revise client briefing maintenance process.
This MR changes the client briefing update process and moves explanation of the client strategy tickets into a dedicated section within the 'Working with Clients' page.
JIRA tickets: https://tasks.opencraft.com/browse/STAR-3095
Discussions: https://forum.opencraft.com/t/ensuring-the-up-to-date-maintenance-of-client-briefings/1556
Testing instructions:
- Check the 'view app' link on this MR to see the changes previewed.
- Verify the formatting looks correct.
Edited by Fox Piacenti