docs: add instructions for protos contribution

[nehalmamgain]

Clarify an important workflow in CONTRIBUTING.md to avoid users adding compiled protos through their own workflows.
Example: related PR with above issue.

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This change is 

[nehalmamgain]

How do I run the linter locally before committing this doc change?
Is there a doc on the repo I can refer for that?

[tk-woven]

Thanks for this! I poked around but did not find docs for any single linting entrypoint. Probably a feature we could add for developer convenience.

Reviewed 1 of 1 files at r1, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @nehalmamgain)

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docs/CONTRIBUTING.md line 81 at r1 (raw file):

**NOTE:** Any [proto schema](../dgp/proto) changes must be seperated from code changes into an independent commit and PR.

Also, please ensure to commit the compiled protos to the aformentioned PR by first running `make build-proto`. 

Thanks! Can you please make this part of the **NOTE:** paragraph? Also, let's reword a little to suggest that we need to run make build-proto and then include the artifacts it produces in the commit and PR.

[nehalmamgain]

Thanks Tyler, I will push your requested changes later today.

[tk-woven]

Reviewed 1 of 1 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @nehalmamgain)