chore: Documentation cleanup and updates (#725)

Some lower level documentation cleanup:
- Convert existing v1 API command documentation to markdwon
- Remove the remaining old stale documentation that is duplicative of other sources
- Rewrite roborock/devices/README.md as simpler higher level documentation focused on library usage
- Copy the existing roborock/devices/README.md which is internal focused into docs/

This establishes docs/ as the internal facing documentation library only, for unsupported features or internal library details.

Author: allenporter

docs/DEVICES.md

@@ -0,0 +1,9 @@
+# Roborock Documentation
+
+This directory contains lower level documentation for developers interested in:
+
+- Details about the lower level transport protocols used by the library
+- Undocumented or unsupported device commands or RPCs
+- The internal design of components of the library
+
+For details about using the library see the higher level documentation at https://python-roborock.github.io/python-roborock/