Remove support for `$INPUT/.gitignore` (0.7.0 added `$ROOT/.gitignore`)

[zachleat]

Breaking change, but almost certainly not necessary.

While I don’t think it’s required to git to place this in your project root, it is the prevailing convention.

Note this on the GitHub docs: https://docs.github.com/en/github/getting-started-with-github/getting-started-with-git/ignoring-files#configuring-ignored-files-for-a-single-repository

You can create a .gitignore file in your repository's root directory to tell Git which files and directories to ignore when you make a commit.

Changed in #229 (comment)

[zachleat]

This repository is now using lodash style issue management for enhancements. This means enhancement issues will now be closed instead of leaving them open.

View the enhancement backlog here. Don’t forget to upvote the top comment with 👍!

[zachleat]

Just for extra clarity, this means we look for ignores in these files in 1.0:

$ROOT/.gitignore
- $INPUT/.gitignore
$ROOT/.eleventyignore
$INPUT/.eleventyignore