Include .gitignore in starters

[MGatner]

Description
devstarter and appstarter both have very old versions of .gitignore - it isn't getting updated when new deployments are made. This PR adds .gitignore to the list of files copied out during a release.

Checklist:

• Securely signed commits

[jim-parry]

Good idea. One teeny change requested :)

[jim-parry]

I have merged this, but I don't think that the gitignore in the framework release prep will make any difference. It will end up in vendor/codeigniter4/framework, which will have no effect on a developer's project.

[MGatner]

How does https://github.com/codeigniter4/devstarter get seeded? That's what really needs the updated files. EDIT: And appstarter of course.

[jim-parry]

It doesn't ... any updates are done manually when there are app changes in a release.

[MGatner]

Ah thanks for clarifying. I misunderstood that deployment script - sorry for the trouble!

[jim-parry]

The appstarter and framework repos are updated as a "normal" part of a release,
That's where the admin/release-appstarter and release-framework scripts are invoked.
This is all done on my system, and then the releases are manually tagged on github.
Not all can be automated, but as much as possible has been :)

[jim-parry]

See admin/README.md and admin/workflow.md