Packaging Practices should have a section on making a patch

[EbonJaeger]

The current documentation only covers applying a patch, which is of little help if the packager doesn't first know how to make a patch file in the first place.

The section should include the following steps:

1. Clone the source repository
2. Make changes to the source
3. Create the patch file
   i. Create a git commit detailing the changes
   ii. Create (if not exists) the files directory inside the package's directory
   iii. Run git format-patch -o ~/path/to/package/dir/files to create the patch file

[Staudey]

Adding Reilly's suggested improvement here before I forget:

If you use git format-patch with the arguments --zero-commit and --no-signature it'll zero out the commit hash and strip the git version from the bottom
This can help reduce the diff from updating the patches in the future a bit