docs: dt: writing-bindings: Document compatible and filename naming

Document established Devicetree bindings maintainers review practices:

1. Compatibles should not use bus suffixes to encode the type of
   interface, because the parent bus node defines that interface, e.g.
   "vendor,device" instead of "vendor,device-i2c" + "vendor,device-spi".

2. If the compatible represents the device as a whole, it should not
   contain the type of device in the name.

3. Filenames should match compatible.  The best if match is 100%, but if
   binding has multiple compatibles, then one of the fallbacks should be
   used.  Alternatively a genericish name is allowed if it follows
   "vendor,device" style.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20250713-dt-bindings-docs-v2-2-672c898054ae@linaro.org


Signed-off-by: Rob Herring (Arm) <robh@kernel.org>