docs: add ST30 III reset note and post-update version-check guidance

Two doc notes from dunha's #621 follow-up: the factory-reset button
combo is confirmed identical on the SoundTouch 30 Series III, and
checking the reported version right after an on-device update can
still show stale info until the speaker (or an open Admin UI tab) is
rebooted, even though the new binary is already running.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

docs/content/docs/guides/ON-DEVICE-INSTALL-WALKTHROUGH.md

@@ -404,6 +404,13 @@ curl -sSLo install.sh https://raw.githubusercontent.com/gesellix/Bose-SoundTouch
 sh install.sh --version 0.123.0
 ```
 
+The script's own final output already confirms the new version came up and
+is answering on `:8000`. If you separately check the version yourself
+(`wget -qO- http://localhost:8000/health`, or the Admin UI), **reboot the
+speaker first**: an Admin UI tab left open from before the update, or a
+browser cache of the previous page load, can otherwise still show the old
+version even though the new binary is already running.
+
 **Rollback:** the installer keeps a `.backup` file alongside the binary:
 
 ```bash

docs/content/docs/guides/TROUBLESHOOTING.md

@@ -653,7 +653,8 @@ Notes:
 
 If the telnet method isn't available for your model, factory reset the speaker, then re-migrate it:
 
-1. Factory reset (on most models: hold `1` + `−` for ~10 seconds).
+1. Factory reset (on most models: hold `1` + `−` for ~10 seconds — confirmed
+   identical on the SoundTouch 30 Series III, not just the original ST30).
 2. Reconnect the speaker to your network.
 3. Re-migrate it in AfterTouch.