docs: update CONTRIBUTING to include build

[VerteDinde]

• I have read the contribution documentation for this project.
• I agree to follow the code of conduct that this project follows, as appropriate.
• The changes are appropriately documented (if applicable).
• The changes have sufficient test coverage (if applicable).
• The testsuite passes successfully on my local machine (if applicable).

Summarize your changes:
After updating our build pipeline, yarn build is no longer run automatically prior to publish as part of the yarn lerna:publish command - it must be run prior to publish. This PR updates the release process docs accordingly

Addresses #4026