Heltec LoRa 32 v3.1 not in documentation

In your [documentation](https://github.com/HelTecAutomation/HeltecDocs/blob/master/doc/node/esp32/source/hardware_update_log.md), Heltec LoRa 32 v3.1 is not shown.

Also, v3.0 is now a dead link in your documentation as it seems you've removed the file.

Mentioned in https://github.com/meshtastic/meshtastic/pull/990