gitignore: ignore config files for the gram editor

[ItsHarper]

Description

Allows Gram users (packaged at #5506) to configure specific settings for cports

Checklist

Before this pull request is reviewed, certain conditions must be met.

The following must be true for all changes:

• I have read CONTRIBUTING.md
• I acknowledge that overtly not following the above or the below will result in my pull request getting closed

The following must be true for template/package changes:

• I have read Packaging.md
• I have built and tested my changes on my machine

The following must be true for new package submissions:

• I will take responsibility for my template and keep it up to date

[subnut]

Wouldn't a system-wide (user-wide?) gitignore (at $XDG_CONFIG_HOME/git/ignore probably) be a better fit for this?

That said, there's already the precedent set by .nvim.lua, so idk...

[ItsHarper]

No. For repos I'm in charge of, I want my per-project settings committed.

As a side tangent, I think most per-project settings should be in the realm of things useful to everyone (build scripts, formatting rules, etc). Your system wide settings are where your individual preferences belong.