Add more detail to developer "Publishing new releases" docs

Include more detail for new devs, including:
- Developer who creates a new feature is usually the one to release the version if required
- What exactly we mean by the semantic version numbering
- When/where/how new features should be advertised (blog, discussions, zulip, slack etc)

When things get released could be:
* Release the package if the changes are useful to users
* Update the metapackage if the changes are important to new users (new versions _should_ be downloaded anyway, updating the metapackage forces it)
* Update workflows if the changes are relevant to a workflow

cc @alessandrofelder

Locate the developer “Publishing new releases” documentation and read its current release guidance first. Expand it to cover who releases feature work, semantic versioning, feature announcements, and when to release packages, metapackages, or workflow updates. Done means each requested point is documented clearly for new developers.

Written by the indexing model from the issue text.