202503 Apache NuttX RTOS Contributing Guidelines update.

* This change comes from vast mailing list discussions on low PR/COMMIT
  quality, breaking changes, code quality, long term self-compatibility
  and maintenance, review problems, and how to improve things.
* Contributing Guidelines updates vote history:
  1. https://www.mail-archive.com/dev@nuttx.apache.org/msg12584.html
  2. https://www.mail-archive.com/dev@nuttx.apache.org/msg12723.html

Signed-off-by: Tomasz 'CeDeROM' CEDRO <tomek@cedro.info>

Author: cederom