reorganize "Shared Memory and LWLocks" section of docs

2024-01-19 17:20:54 Nathan Bossart (bossartn) Closed in commitfest 2024-03 with status: Committed 2024-01-17 01:18:28 Bharath Rupireddy (bharathrupireddy) Added bharathrupireddy as reviewer 2024-01-13 21:42:10 Nathan Bossart (bossartn) New status: Ready for Committer 2024-01-13 21:42:08 Nathan Bossart (bossartn) Added bossartn as committer 2024-01-12 04:15:20 Nathan Bossart (bossartn) Changed authors to Nathan Bossart (bossartn) 2024-01-12 04:15:20 Nathan Bossart (bossartn) Changed targetversion to 17 2024-01-12 04:15:14 Nathan Bossart (bossartn) Attached mail thread 20240112041430.GA3557928@nathanxps13 2024-01-12 04:15:14 Nathan Bossart (bossartn) Created patch record