Migration of STM32 to new documentation

[raiden00pl]

The current documentation is very confusing now, there are almost no ST chips in it, when in reality ST is probably the best supported MCU vendor.

So I started moving READMEs from boards to Documentation.

I think it's better to have it in Documentation, even in a working state with bad formatting than as it is now.

TODOs:

• STM32F0 - Documentation: migrate STM32F0 #10362
• STM32F1 - Documentation: migrate STM32F1 #10377
• STM32F2 - Documentation: migrate STM32F2 #10367
• STM32F3 - Documentation: migrate STM32F3 #10371
• STM32F4 - Documentation: migrate STM32F4 #10374
• STM32F7 - Documentation: migrate STM32F7 #10376
• STM32H7 - Documentation: migrate STM32H7 #10368
• STM32L0 - Documentation: migrate STM32L0 #10364
• STM32L1 - Documentation: migrate STM32L1 #10369
• STM32L4 - Documentation: migrate STM32L4 #10375
• STM32L5 - Documentation: migrate STM32L5 #10373
• STM32G0 - Documentation: migrate STM32G0 #10363
• STM32G4 - Documentation: migrate STM32G4 #10366
• STM32U5 - Documentation: migrate STM32U5 #10372
• STM32WB - Documentation: migrate STM32WB #10365
• STM32WL5 - already upstream

[raiden00pl]

Initial migration complete. But it's still a lot of work to make it look good.

But at least we have a list of supported chips in a prominent place.