Add support for forks

[SirSpidey]

Description

See a comment in the internal issue #3813 for a link to where this draft is published internally.

---

Info about contributing a new module still uses a clone. Let me know if the workflow will instead be that the contributor forks the module that we create.

---

• Adds a topic that describes how to fork a repo to update it.
• Content that is now reused is moved to include files.
• Changes title of topic about updating an older module to Porting to distinguish from new topic.

Release required?

• No release
• Patch release (x.x.X)
• Minor release (x.X.x)
• Major release (X.x.x)

Release notes content

Run the pipeline

If the CI pipeline doesn't run when you create the PR, the PR requires a user with GitHub collaborators access to run the pipeline.

Run the CI pipeline when the PR is ready for review and you expect tests to pass. Add a comment to the PR with the following text:

/run pipeline

Checklist for reviewers

• If relevant, a test for the change is included or updated with this PR.
• If relevant, documentation for the change is included or updated with this PR.

For mergers

• Use a conventional commit message to set the release level. Follow the guidelines.
• Include information that users need to know about the PR in the commit message. The commit message becomes part of the GitHub release notes.
• Use the Squash and merge option.

[SirSpidey]

@daniel-butler-irl: Recombined the contributing topic to support both new modules and updating modules. Removed the step when forking to Copy the main branch only.

You can see the internal version at https://pages.github.ibm.com/allen-dean/tim-docs/#/contribute-module

[daniel-butler-irl]

Great, looks good now. One thing I saw is, we now have a doc gap. Not sure if it goes in this PR. Now we accept forks it means external contributors can contribute. These users will not have access to trigger the pipeline. The Open pull request section needs to be updated to state, if you are a member of github-collaborators you can trigger the pipeline. Then the next part we need to figure out is for external contributors maybe ask to notify @terraform-ibm-modules/github-admins @ocofaigh what do you think about this?

The merge-base changed after approval.

The merge-base changed after approval.

The merge-base changed after approval.

The merge-base changed after approval.

The merge-base changed after approval.

The merge-base changed after approval.

The merge-base changed after approval.

The merge-base changed after approval.

The merge-base changed after approval.

[SirSpidey]

Closed in favor of #52 because this PR keeps dismissing reviews.