docs: update GPS page for every-boot u-blox reconfiguration

[mairas]

Summary

• Update HALPI2 paragraph on GPS page to reflect that u-blox receivers are reconfigured on every boot
• Explain why: MAX-M8Q is ROM-based with no flash, settings stored in BBR only
• Note the ~2 second transparent delay

🤖 Generated with Claude Code

[mairas]

Code Review

Overall: Clean, well-scoped change. The added context about ROM-based modules and BBR is accurate and helpful for users who might wonder why reconfiguration happens on every boot. The HALPI2 and GNSS documentation links are preserved.

One issue to address

Timing claim (should fix): The text says "approximately 2 seconds" but verified measurements show 2-4 seconds. Suggesting either "approximately 2-4 seconds" or just "a few seconds" to avoid understating what users may observe. If a user sees 4 seconds and the docs say "approximately 2," they might think something is wrong.

Everything else looks good

• Technical claims are accurate: MAX-M8Q is indeed ROM-based with no flash, and UBX-CFG-CFG can only persist to BBR on these modules
• "may be lost on power cycles" is correctly hedged (BBR survives warm resets but not cold power loss without battery)
• Adding 115200 bps to the parenthetical is useful -- it was missing before and is a configuration change users might notice
• "transparent" is the right word -- no user action required
• The sentence is on the long side but reads clearly and keeps all the context in one place without forcing readers to jump around

Approved pending the timing wording fix.