Document Network Timeout/Periodically Sync Media

Network timeout and periodically sync media isn't documented in the manual. Here is where it should go: https://docs.ankiweb.net/syncing.html#syncing

Network timeouts sometimes help if you're facing issues with syncing and that needs be mentioned.

Open the manual's syncing section at the linked URL and review the existing guidance. Document network timeouts and periodic media syncing there; the work is done when both topics are clearly explained in that section.

Written by the indexing model from the issue text.