Chore: update precommit hook to insert URLs and mod names

[aclist]

Update the maintainer's precommit hook so that mod authors don't have to update megamod.user.js at all with @requiresor touch the funcObj. The author can just:

• Test the mod locally using whatever URLs they want for the source mod

When making the PR:

• Update the manifest.json
• Add the mod to the mods directory
• That's it.

The hook will be responsible for updating megamod.user.js with the correct path to the resource and updating the funcObj. This should reduce the problem of having the wrong URLs or names making their way into the PR and ensure that after the mod is tested and approved, the resources are updated programmatically, along with the version bump, for one unified change.

• Add this to documentation
• Optional: for maintainability, consider parameterizing and regenerating the entire header based on the manifest of mods to flexibly support URL/branch changes/supported GM API calls

[aclist]

Resolved by 85060d43fdc7f12a02d6e9a04c1248dedfbff9ee