docs: re-write CONTRIBUTING.md (#36)

* docs: re-write CONTRIBUTING.md

* build: add changelog to gitignore

CONTRIBUTING.md

@@ -1,10 +1,16 @@
 # Contributing
 
-Thank you for considering to contribute to `metapac`. The recommended workflow is
-this:
+Thank you for considering to contribute to `metapac`, all contributions are
+welcome!
 
-1. Open a github issue, mention that you would like to fix the issue in a PR.
-2. Wait for approval.
-3. Fork the repository and implement your fix / feature.
-4. Make sure your code generates no warnings, and passes `rustfmt` and `clippy`.
-5. Open the pull request.
+There are no hard rules for this project but there are some general
+guidelines to avoid problems:
+
+- Open github issues for any features/bugs/issues you want to raise, but
+  try to check the existing issues to avoid duplicates.
+- Try to comment on an issue before attempting any pull requests to avoid
+  multiple people working on the same feature at the same time which would
+  result in wasted effort.
+- Discussion is always welcome on issues since there are usually multiple
+  ways to fix/implement every bug/feature and discussion is the best and
+  easiest way to select the best solution.

typos.toml

@@ -0,0 +1,2 @@
+[files]
+extend-exclude = ["CHANGELOG.md"]