[FSDEV] Update the STM32 documentation

[Okarss]

Seeing the upcoming #2672, also added U535/U545 as supported.

[Okarss]

Looking more into supported.rst ...

| G4                    | ✔      | ✖    | ✖         | stm32_fsdev       |
| WBx5                  | ✔      |      |           | stm32_fsdev       |

The hardware of both are of a full-speed USB device type. It seems that there is a confusion of what exactly the ✖ and empty box means. Currently both are used for two options:

• Not supported by hardware.
• Hardware capable, but not supported by software implementation.

To improve the clarity I propose changing the meaning and explanation to this:

• Empty - Not supported by hardware.
• ✖ - Hardware capable, but not supported by software implementation.

That way, if there is any symbol present, it means that the hardware is capable of that particular feature and the symbol itself just shows the status of the software implementation. To me such an approach seems to be more useful and consistent. If the main developers agree to such a change, I could at least update this for STM32 devices and probably some other.

Any comments?

[hathach]

actually, I don't manage the docs well enough. The idea is

• ✔: tested and worked
• ✖: hw is not supported
• (empty): no information, maintainer just forgot or have no idea.

If you are user WBx5 is FS device only, please make a pr to update it.

[Okarss]

Also slightly updated the table legend. As there are no functional changes, despite the failing hardware test, this PR is ready to go.

[HiFiPhile]

Table looks good, somehow legend is not shown

[hathach]

Table looks good, somehow legend is not shown

[ ] is an syntax, I think we need to escape it, or just use (empty) or simply "empty"/empty instead

[Okarss]

Sorry for the blunder! I wasn't familiar with RST syntax and didn't pay enough attention to that smaller table. Now learned a bit about the syntax, used this online editor and it seems that the latest commit is finally correct.