Add CONTRIBUTING.md and remove roadmap

Author: ThomasGravekamp

CONTRIBUTING.md

@@ -0,0 +1,22 @@
+# Contributing to the STM32-base project documentation
+
+Thank you for showing interest in contributing to the STM32-base project documentation!
+
+## Scope
+
+The scope of the STM32-base documentation is broad. It can be divided in four categories:
+
+ - Guides and concept pages on Arm Cortex-M cores
+ - Guides and concept pages on STM32 microcontrollers and development boards
+ - Guides and concept pages specific to STM32-base
+ - Guides and concept pages on other projects supporting STM32 microcontrollers
+
+The last category is a special one. Guides and concept pages on other projects are allowed. However, maintaining these pages will be a responsibility of their author or their project's team.
+
+## Reporting an issue
+
+Issues must be reported on Github. You can create an issue for (spelling) errors, ideas, features, and questions. Issues found in the STM32-base project itself must be reported on the [STM32-base repository](https://github.com/STM32-base/STM32-base).
+
+## Creating a pull request
+
+If you are able to fix or add something yourself, please do so! You can proceed without reporting an issue for small fixes or for new pages. Please report an issue if you want to work on something bigger.

general/roadmap.md

@@ -26,4 +26,4 @@ The STM32-base project is divided over multiple Github repositories. See the [pr
 
 ## Contributing
 
-Refer to the [`CONTRIBUTING.md`](https://github.com/STM32-base/STM32-base/blob/master/CONTRIBUTING.md) file to learn more about contributing to the STM32-base project. Take a look at the [roadmap]({{ site.url }}/general/roadmap) if you are looking for things to work on.
+Refer to the [`CONTRIBUTING.md`](https://github.com/STM32-base/STM32-base/blob/master/CONTRIBUTING.md) file of the STM32-base repository to learn more about contributing to the STM32-base project. Refer to the [`CONTRIBUTING.md`](https://github.com/STM32-base/STM32-base.github.io/blob/master/CONTRIBUTING.md) file of the STM32-base project documentation repository to learn more about contributing to this documentation website.