Document contributing guidelines (#66)

- Document contributing guidelines

Reviewed-on: https://git.mills.io/prologic/tube/pulls/66
Co-authored-by: Heinrich 'Henrik' Langos <gumbo2000@noreply@mills.io>
Co-committed-by: Heinrich 'Henrik' Langos <gumbo2000@noreply@mills.io>

CONTRIBUTING.md

@@ -0,0 +1,60 @@
+# Contributing to tube
+
+We welcome contributions from the community and are grateful for any help you can provide!
+
+## Pull Request Conventions
+
+We are using tools to process pull requests. When submitting a pull request,
+please follow these conventions. That way can automatically generate the [CHANGELOG.md](CHANGELOG.md).
+
+- Please put a brief description of the changes made in the pull request title.
+- If you want the changes to show up in the changelog start the title with
+  one of the following words:
+    - "Fix" for bug fixes,
+    - "Add" for new features,
+    - "Document" for changes to the documentation,
+    - "Update" for updates of dependencies,
+- Include a description of the changes in the pull request body.
+  If the changes are not obvious, try to concentrate on the "why" instead of the "what".
+  Later developers can always look at the code and see what is going on.
+  They can not look into your mind and see "why" you decided to implement it a certain way.
+- Include links to the issues that are closed by this PR using the
+  format `- Closes #issue_number` or `- Resolves #issue_number`.
+
+### Example Pull Request
+#### Title
+```
+Fix missing validation of input in login screen
+```
+
+#### Body
+
+```
+The issue was caused by a missing validation check in the login function.
+It allowed users to put in values that will be declined by the login handler anyway.
+I have added the necessary validation check and added the appropriate error messages,
+so the users have instant feedback instead of an error message after submitting the
+login form.
+
+- Closes #123
+```
+
+## Squashing Commits
+
+Please note that all pull requests will be squashed before merging.
+This means that multiple commits on a branch will be combined into
+a single commit on the master branch. This helps keep the master
+branch history clean and easy to understand.
+
+The pull request's title and body will be used for that squashed commit.
+It will become part of the project's history and a help the next developer
+to understand the changes that happened.
+
+## Code of Conduct
+
+This project does not have a written code of conduct. Be nice to each other!
+If you need further instructions ask your parents or the Dalai Lama. ;-)
+
+## Thank you
+
+Thank you for considering contributing to tube. We appreciate your help and support!

README.md

@@ -270,7 +270,7 @@ used it in their own projects or products, fixed bugs, improved performance
 and even fix tiny typos in documentation! Thank you and keep contributing!
 
 You can find an [AUTHORS](AUTHORS) file where we keep a list of contributors
-to the project. If you contriibute a PR please consider adding your name there.
+to the project. If you contribute a PR please consider adding your name there.
 There is also Github's own [Contributors](https://git.mills.io/prologic/tube/graphs/contributors) statistics.
 
 [![](https://sourcerer.io/fame/prologic/prologic/tube/images/0)](https://sourcerer.io/fame/prologic/prologic/tube/links/0)
@@ -283,6 +283,6 @@ There is also Github's own [Contributors](https://git.mills.io/prologic/tube/gra
 tube source code is available under the MIT [License](LICENSE).
 
 Previously based off of [tube](https://github.com/wybiral/tube) by [davy wybiral
-](https://github.com/wybiral). (See [LICENSE.old](LICENSE.old))
+](https://github.com/wybiral).
 
 App icon is licensed under the Apache license from Google Noto Emoji.