Add "content" release type to commit-lint and release-please

[NoopDog]

Need

The site is primarily a content site, so we would like to add the commit type content, which is not a standard Conventional Commit type. This can be an alternative to docs, as docs are about web implementation and not content.

Approach

1. Add content as a valid commit type for commit lint.
2. Modify the release-please-config.json to use a "Content" section for the content commit type.

Thanks!

[NoopDog]

Complete