Update contributing instructions

Author: greenrobot-team

CONTRIBUTING.md

@@ -1,22 +1,24 @@
-Contributing
-------------------
-This project is completely managed on GitHub using its [issue tracker](https://github.com/objectbox/objectbox-dart/issues).
+# Contributing
 
-Anyone can contribute, be it by coding, improving docs or just proposing a new feature. 
+For public issues see the [GitHub issue tracker](https://github.com/objectbox/objectbox-dart/issues).
+
+We welcome smaller contributions, be it by coding, improving docs or just proposing a new feature. 
 Look for tasks having a [**"help wanted"**](https://github.com/objectbox/objectbox-dart/issues?q=is%3Aissue+is%3Aopen+label%3A%22help+wanted%22) tag. 
-When picking up an existing issue, please let us know in the issue comment. 
+When picking up an existing issue, please talk to us beforehand by commenting in the issue. 
 Don't hesitate to reach out for guidance or to discuss a solution proposal!
 
-### Code contributions
+## Code contributions
+
 When creating a Pull Request for code changes, please check that you cover the following:
-* Include tests for the changes you introduce. See the [test folder](objectbox/test) for examples.
-* Formatted the code using `dartfmt -l 120`. You can configure your IDE to do this automatically, 
-  e.g. VS Code needs the project-specific settings `"editor.defaultFormatter": "Dart-Code.dart-code"` and `"dart.lineLength": 120`.
-* Update the `## latest` section in the `CHANGELOG.md` - add a single-line comment what changes.
-  This only applies if the change is "external", i.e. it affects objectbox-dart library users.
 
-### Basic technical approach
+- Include tests for the changes you introduce. See the [test package](objectbox_test) for examples.
+- Formatted your changes using `dart format`.
+- If the change affects users of this library, update the `## latest` section in the `CHANGELOG.md` 
+  by adding a single-line comment what changes.
+
+## Basic technical approach
+
 ObjectBox offers a [C API](https://github.com/objectbox/objectbox-c) which can be called by [Dart FFI](https://dart.dev/server/c-interop).
 The C API is also used by the ObjectBox language bindings for [Go](https://github.com/objectbox/objectbox-go), [Swift](https://github.com/objectbox/objectbox-swift), and [Python](https://github.com/objectbox/objectbox-python).
 These languages may serve as an inspiration for this Dart implementation.
-Internally, ObjectBox uses [FlatBuffers](https://google.github.io/flatbuffers/) to store objects.
+Internally, ObjectBox uses [FlatBuffers](https://google.github.io/flatbuffers/) to store objects.