core: frontend: ardupilot-manager: link to firmware docs

### Current behaviour

The "Autopilot Firmware" page displays the detected vehicle type and firmware version, but no information about what functionality or features are included in that.

### Expected or desired behaviour

It seems like it shouldn't be too complicated to create a mapping that also provides a link to the documentation of a the relevant firmware version for that vehicle type.

We could also conceivably create an extension that locally hosts the relevant docs, but to start with it seems fine to just auto-generate a hyperlink to the online docs for the currently active vehicle firmware, or the most recent ones if the firmware is custom / has an unknown version.

### Prerequisites

- [X] I have checked to make sure that a similar request has not already been filed or fixed.