updating and renaming CONTRIBUTING file

CONTRIBUTING.md

@@ -0,0 +1,33 @@
+How to contribute
+=================
+
+If you want to contribute to the libraries in any way such as adding new components
+or fixing existing ones, you are more than welcome to submit a pull request on GitHub for
+the relevant repository.
+
+If you are new to GitHub, please check out this guide
+[Contributing to Open Source on GitHub](https://guides.github.com/activities/contributing-to-open-source)
+before you start.
+
+When creating/editing/fixing a symbol or footprint a set of conventions (a.k.a rules)
+should be followed. They are the
+[KiCad Library Convention](https://github.com/KiCad/kicad-library/wiki/Kicad-Library-Convention),
+or KLC for short. This convention aims to make symbols and footprints have a
+unique standard which is valuable in many aspects. Please, read the KLC carefully and
+make sure your pull request is compliant with it. Librarians often are very demanding
+about respecting the KLC.
+
+Note that the KLC is in some way a newcomer, this mean there are several symbols and
+footprints in the KiCad repositories that are not KLC compliant yet. However,
+there is an [effort](https://github.com/KiCad/kicad-library/wiki/Status-of-the-libraries)
+to make all libraries KLC compliant. You can also help by doing some work in this
+direction.
+
+When possible, take an already existing KLC symbol/footprint as an example to
+create/edit symbols and/or footprints. Furthermore, you can use the
+[kicad-library-utils](https://github.com/KiCad/kicad-library-utils) scripts to help
+you check/fix KLC issues. For more information about how to use the scripts
+please look at the README.md file in the repository. It is important to know that the
+scripts does not cover all KLC rules, which means that if you got no issues reported
+by script, this does not imply your submission will be accepted or that it is not
+violating the KLC rules.