rust: add docs

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Author: bonzini

docs/devel/index-process.rst

@@ -17,3 +17,4 @@ Notes about how to interact with the community and how and where to submit patch
    stable-process
    submitting-a-pull-request
    secure-coding-practices
+   rust