Add documentation for the RPMsg dump command, which is a diagnostic
tool for dumping RPMsg debugging information. The document covers:
- Command usage and syntax
- Output description including CPU info, endpoint list, virtqueue
dump, and buffer states
- Common debugging use cases such as TX buffer timeout issues,
communication failures, and buffer leak detection
Signed-off-by: Bowen Wang <wangbowen6@xiaomi.com>
97b64010cd