Add a reminder for first-time contributors (#3940)

>
> * Update CONTRIBUTING.md CREDITS.md
>
> * If there is a file for contributors, why not telling them when they check the guidelines?

CONTRIBUTING.md

@@ -31,7 +31,7 @@ Did you want to fix a bug? To keep a great coordination between collaborators, y
 1. Be sure the bug is associated to a ticket and say you work on it.
 2. [Fork this project repository](https://help.github.com/articles/fork-a-repo/).
 3. [Create a new branch](https://help.github.com/articles/creating-and-deleting-branches-within-your-repository/). The name of the branch must be explicit and being prefixed by the related ticket id. For instance, `783-contributing-file` to fix [ticket #783](https://github.com/FreshRSS/FreshRSS/issues/783).
-4. Make your changes to your fork and [send a pull request](https://help.github.com/articles/using-pull-requests/) on the **edge branch**.
+4. Make your changes to your fork and [send a pull request](https://help.github.com/articles/using-pull-requests/) on the **edge branch**. Don't forget to add your name to CREDITS.md if you're contributing to FreshRSS for the very first time.
 
 If you have to write code, please follow [our coding style recommendations](https://freshrss.github.io/FreshRSS/en/developers/01_First_steps.html).
 

CREDITS.md

@@ -64,6 +64,7 @@ People are sorted by name so please keep this order.
 * [Jules Bertholet](https://github.com/Jules-Bertholet): [contributions](https://github.com/FreshRSS/FreshRSS/pulls?q=is:pr+author:Jules-Bertholet)
 * [Julien Reichardt](https://github.com/j8r): [contributions](https://github.com/FreshRSS/FreshRSS/pulls?q=is:pr+author:j8r), [Web](https://blog.jrei.ch/)
 * [Julien-Pierre Avérous](https://github.com/javerous): [contributions](https://github.com/FreshRSS/FreshRSS/pulls?q=is:pr+author:javerous), [Web](https://www.sourcemac.com/)
+* [Kaibin Yang](https://github.com/SkyYkb): [contributions](https://github.com/FreshRSS/FreshRSS/pulls?q=is:pr+author:SkyYkb), [Web](https://kaibinyang.com/)
 * [Kevin Papst](https://github.com/kevinpapst): [contributions](https://github.com/FreshRSS/FreshRSS/pulls?q=is:pr+author:kevinpapst), [Web](http://www.kevinpapst.de/)
 * [Kiblyn11](https://github.com/Kiblyn11): [contributions](https://github.com/FreshRSS/FreshRSS/pulls?q=is:pr+author:Kiblyn11)
 * [kinoushe](https://github.com/kinoushe): [contributions](https://github.com/FreshRSS/FreshRSS/pulls?q=is:pr+author:kinoushe)