Summary:
Due to offline discussion, we use actual url of the clang-format-diff.py and add a note.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7950
Reviewed By: pdillinger
Differential Revision: D26370822
Pulled By: riversand963
fbshipit-source-id: 7508e23c002d56d5c1649090438ef5f8ff2cdbe7