Add guidance for package maintenance

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Cover topics like:

- Use the module template
- Follow SemVer
- Changelog maintenance
- Testing prerelease builds locally and on CI
- e.g. yarn link or file:// for local, preview builds for CI
- dependencies vs peerDependencies vs devDependencies

Notes:
This message was on Slack and should be included in the guidelines in some way:
PSA: There are two primary ways that we communicate changes we've make to our NPM packages to consumers. Changelogs are one of them, but we also use versions as a coarse indicator as well. I have seen several instances over time where a version for a released package was bumped in a way that either oversells or undersells the changes inside of that release. For instance:

- Bumping the minor part of a version if new functionality was not being added, when only the patch should have been bumped
- Bumping only the patch part of a version when new functionality was added, when the minor should have been bumped
- Not bumping the major part of a version when breaking changes are introduced

As a reminder, we use [SemVer](https://semver.org/) to assign new versions for packages. I would recommend everyone read this when they get a chance, especially the "Why Use" section and the FAQ.

Inizia esaminando la documentazione esistente per i contributori e le indicazioni SemVer collegate, quindi identifica dove inserire le indicazioni sulla manutenzione dei pacchetti. Tratta il template del modulo, il versionamento, i changelog, i test delle versioni prerelease, i tipi di dipendenze e i workflow locali e di CI elencati nell’issue. Il lavoro è completo quando questi argomenti sono documentati chiaramente per i contributori dei pacchetti.

Scritto dal modello di indicizzazione a partire dal testo della issue.