Can the README.md include what's the difference between this plugin and the `pyi` plugin

[kalfa]

--pyi_out=foo vs protoc-gen-mypy_grpc: both create typing stubs.

The pyi is by default present in protoc. Is it possible to add a description about difrerences to this and other similar plugin (if any), please?

this will help user adoption. I am trying to understand myself if this would benefit me more than the standard pyi plugin

[nipunn1313]

sounds useful! PRs accepted!