Fix tests and move contributing docs into our docs (#133)

Author: choldgraf

CONTRIBUTING.md

@@ -0,0 +1 @@
+See [the contributing guide in the documentation](docs/contribute.md).

docs/contribute.md

@@ -30,7 +30,7 @@ nox -s docs -- live
 
 The easiest way to make a release is to follow these steps:
 
-1. **Bump the version in `__init__.py` and push it to master**.
+1. **Bump the version in `__init__.py` and push it to main**.
    We try to use [semver version numbers](https://semver.org/) but don't stress out about it too much.
    - In your commit message use something like `RLS: vX.Y.Z`.
    - Add a changelog to `CHANGELOG.md`[^1].

tests/test_cli/test_contributor_sorting.md

@@ -29,4 +29,4 @@ See [our definition of contributors](https://github-activity.readthedocs.io/en/l
 
 ([GitHub contributors page for this release](https://github.com/jupyter-book/mystmd/graphs/contributors?from=2025-07-05&to=2025-07-21&type=c))
 
-@agoose77 ([activity](https://github.com/search?q=repo%3Ajupyter-book%2Fmystmd+involves%3Aagoose77+updated%3A2025-07-05..2025-07-21&type=Issues)) | @brian-rose ([activity](https://github.com/search?q=repo%3Ajupyter-book%2Fmystmd+involves%3Abrian-rose+updated%3A2025-07-05..2025-07-21&type=Issues)) | @brianhawthorne ([activity](https://github.com/search?q=repo%3Ajupyter-book%2Fmystmd+involves%3Abrianhawthorne+updated%3A2025-07-05..2025-07-21&type=Issues)) | @bsipocz ([activity](https://github.com/search?q=repo%3Ajupyter-book%2Fmystmd+involves%3Absipocz+updated%3A2025-07-05..2025-07-21&type=Issues)) | @choldgraf ([activity](https://github.com/search?q=repo%3Ajupyter-book%2Fmystmd+involves%3Acholdgraf+updated%3A2025-07-05..2025-07-21&type=Issues)) | @kp992 ([activity](https://github.com/search?q=repo%3Ajupyter-book%2Fmystmd+involves%3Akp992+updated%3A2025-07-05..2025-07-21&type=Issues)) | @rowanc1 ([activity](https://github.com/search?q=repo%3Ajupyter-book%2Fmystmd+involves%3Arowanc1+updated%3A2025-07-05..2025-07-21&type=Issues)) | @stefanv ([activity](https://github.com/search?q=repo%3Ajupyter-book%2Fmystmd+involves%3Astefanv+updated%3A2025-07-05..2025-07-21&type=Issues))
+@agoose77 ([activity](https://github.com/search?q=repo%3Ajupyter-book%2Fmystmd+involves%3Aagoose77+updated%3A2025-07-05..2025-07-21&type=Issues)) | @brian-rose ([activity](https://github.com/search?q=repo%3Ajupyter-book%2Fmystmd+involves%3Abrian-rose+updated%3A2025-07-05..2025-07-21&type=Issues)) | @brianhawthorne ([activity](https://github.com/search?q=repo%3Ajupyter-book%2Fmystmd+involves%3Abrianhawthorne+updated%3A2025-07-05..2025-07-21&type=Issues)) | @bsipocz ([activity](https://github.com/search?q=repo%3Ajupyter-book%2Fmystmd+involves%3Absipocz+updated%3A2025-07-05..2025-07-21&type=Issues)) | @choldgraf ([activity](https://github.com/search?q=repo%3Ajupyter-book%2Fmystmd+involves%3Acholdgraf+updated%3A2025-07-05..2025-07-21&type=Issues)) | @kp992 ([activity](https://github.com/search?q=repo%3Ajupyter-book%2Fmystmd+involves%3Akp992+updated%3A2025-07-05..2025-07-21&type=Issues)) | @naokic3 ([activity](https://github.com/search?q=repo%3Ajupyter-book%2Fmystmd+involves%3Anaokic3+updated%3A2025-07-05..2025-07-21&type=Issues)) | @rowanc1 ([activity](https://github.com/search?q=repo%3Ajupyter-book%2Fmystmd+involves%3Arowanc1+updated%3A2025-07-05..2025-07-21&type=Issues)) | @stefanv ([activity](https://github.com/search?q=repo%3Ajupyter-book%2Fmystmd+involves%3Astefanv+updated%3A2025-07-05..2025-07-21&type=Issues))