Typo in readme local dev part

[nirnayroy]

The command
bash ./generate-protos.sh
for local development errors out due to no file present. Assuming it meant
bash ./generate_protos.sh

Since the other other files have underscores and not dashes. I think the filename needs to be changed and not the readme. Since the change is trivially small, have opened a PR in case it helps the maintainers.