add CONTRIBUTING.md (#2893)

* add a basic CONTRIBUTONG.md

* link CONTRIBUTING.md from README.md

* add links, slight rewordings

* Update CONTRIBUTING.md

Co-authored-by: link2xt <link2xt@testrun.org>

* use links redirecting to the user's locale

* Update CONTRIBUTING.md

---------

Co-authored-by: link2xt <link2xt@testrun.org>

CONTRIBUTING.md

@@ -0,0 +1,153 @@
+# Contributing Guidelines
+
+Thank you for looking for ways to help on Delta Chat Android!
+
+This document tries to outline some conventions that may not be obvious
+and aims to give a good starting point to new contributors.
+
+
+## Reporting Bugs
+
+If you found a bug, [report it on Github](https://github.com/deltachat/deltachat-android/issues).
+
+Project maintainers may transfer bugs that are not UI specific
+(eg. network, database or encryption related)
+to [Delta Chat Core](https://github.com/deltachat/deltachat-core-rust/issues).
+If you assume beforehand, that the bug you've found belongs to Core,
+you can report there directly.
+
+Please search both open and closed issues to make sure your bug report is not a duplicate.
+
+For community interactions around Delta Chat
+please read our [Community Standards](https://delta.chat/community-standards).
+
+
+## Proposing Features
+
+If you have a feature request,
+create a new topic on the [Forum](https://support.delta.chat/c/features/6).
+
+
+## Rough UX Philosophy
+
+Some rough ideas, that may be helpful when thinking about how to enhance things:
+
+- Work hard to avoid options and up-front choices.
+  Thinking about concrete user stories may help on that
+- Avoid to speak about keys and other hard to understand things in the primary UI
+- The app shall work offline as well as with bad network
+- Users do not read (much)
+- Consistency matters
+- Offer only things that are highly useful to many people in primary UI.
+  If really needed, bury other things eg. in some menus
+- The app should be for the many, not for the few
+
+
+## Contributing Code
+
+The [README](./README.md) explains in detail how to set up the build environment.
+Please follow all steps precisely.
+If you run into troubles,
+ask on of the [cummunication channels](https://delta.chat/contribute) for help.
+
+To contribute code,
+[open a Pull Request](https://github.com/deltachat/deltachat-android/pulls).
+
+If you have write access to the repository,
+push a branch named `<username>/<feature>`
+so it is clear who is responsible for the branch,
+and open a PR proposing to merge the change.
+Otherwise fork the repository and create a branch in your fork.
+
+Please add a meaningful description to your PR
+so that reviewers get an idea about what the modifications are supposed to do.
+
+A meaningful PR title is helpful for [updating `CHANGELOG.md` on releases](./RELEASE.md)
+(CHANGELOG.md is updated manually
+to only add things that are at least roughly understandable by the end user)
+
+If the changes affect the user interface,
+screenshots are very helpful,
+esp. before/after screenshots.
+
+
+### Coding Conventions
+
+Source files are partly derived from different other open source projects
+and may follow different coding styles and conventions.
+
+If you do a PR fixing a bug or adding a feature,
+please embrace the coding convention you see in the corresponding files,
+so that the result fits well together.
+
+Do not refactor or rename things in the same PR
+to make the diff small and the PR easy to review.
+
+Project language is Java.
+
+By using [Delta Chat Core](https://github.com/deltachat/deltachat-core-rust)
+there is already a strong separation between "UI" and "Model".
+Further separations and abstraction layers are often not helpful
+and only add more complexity.
+
+Try to avoid premature optimisation
+and complexity because it "may be needed in some future".
+Usually, it is not.
+
+Readable code is better than having some Java paradigms fulfilled.
+Classic Java has a strong drive to add lots of classes, factories, one-liner-functions.
+Try to not follow these patterns and keep things really on point and simple.
+If this gets in conflict with embracing existing style, however,
+consistency with existing code is more important.
+
+The "Delta Chat Core" is a high-level interface to what the UI actually needs,
+data should be served in a form that the UI do not need much additional work.
+If this is not the case, consider a feature proposal to "Delta Chat Core".
+
+
+### Merging Conventions
+
+PR are merged usually to the branch `main` from which [releases](./RELEASE.md) are done.
+
+As a default, do a `git rebase main` in case feature branches and `main` differ too much.
+
+Once a PR has an approval, unless stated otherwise, it can be merged by the author.
+A PR may be approved but postponed to be merged eg. because of an ongoing release.
+
+To ensure the correct merge merge strategy, merging left up to the PR author:
+
+- Usually, PR are squash-merged
+  as UI development often results in tiny tweak commits that are not that meaningful on their own.
+- If all commits are meaningful and have a well-written description,
+  they can be rebased-merged.
+
+If you do not have write access to the repository,
+you may leave a note in the PR about the desired merge strategy.
+
+
+## Translations
+
+Translations are done via [Transifex](https://explore.transifex.com/delta-chat/),
+you can log in there with your E-Mail Address or with a Github or Google handle.
+You find two projects there:
+- "Delta Chat App" contains the strings used in the app's UI
+- "Delta Chat Website" contains the offline help from "Settings / Help"
+  as well as the pages used on <https://delta.chat>
+
+Most strings and the whole help are used for all systems
+(Android, iOS, Linux, Windows, macOS)
+and should be formulated accordingly.
+
+If you want to change the english sources,
+do a PR to [`strings.xml`](https://github.com/deltachat/deltachat-android/blob/main/res/values/strings.xml)
+or to [`help.md`](https://github.com/deltachat/deltachat-pages/blob/master/en/help.md).
+Again, please do not mix adding things and refactorings, esp. for `help.md`,
+this would require retranslations and should be considered carefully.
+
+
+## Other Ways To Contribute
+
+For other ways to contribute, refer to the [website](https://delta.chat/contribute).
+
+If you think, something important is missed in this overview,
+please do a PR to this document :)

README.md

@@ -8,6 +8,8 @@ The APK can also be downloaded from [get.delta.chat](https://get.delta.chat).
 For the core library and other common info, please refer to the
 [Delta Chat Core Library](https://github.com/deltachat/deltachat-core-rust).
 
+For general contribution hints, please refer to [CONTRIBUTING.md](./CONTRIBUTING.md).
+
 <img alt="Screenshot Chat List" src="docs/images/2019-01-chatlist.png" width="298" /> <img alt="Screenshot Chat View" src="docs/images/2019-01-chat.png" width="298" />