Add reserved option range for mypy-protobuf

Mypy-protobuf is here
https://github.com/nipunn1313/mypy-protobuf

It currently uses extensions as explained here.
https://github.com/nipunn1313/mypy-protobuf/blob/main/proto/mypy_protobuf/extensions.proto

It's a fairly stable project for generating type stubs for protobuf.
It's been around since ~2015 (open source since 2017). Since open
sourcing it, it would make sense to reserve some extension numbers in
the global range.

See
https://github.com/nipunn1313/mypy-protobuf/issues/396

docs/options.md

@@ -340,3 +340,7 @@ with info about your project (name and website) so we can add an entry for you.
 1. Oclea Service Layer RPC
    * Website: https://oclea.com/
    * Extension: 1150
+
+1. mypy-protobuf
+   * Website: https://github.com/nipunn1313/mypy-protobuf
+   * Extension: 1151-1159