Add DocRaptor logo (#284)

In version v2.0.0 of the docraptor package we decided to drop support
for Python 2.

As stated in our repo, all development moving forward will only be done
using Python 3.

Any links to any relevant tickets, articles or other resources?
---------------------------------------------------------------
https://pypi.org/project/docraptor/
DocRaptor/docraptor-python#11

Co-authored-by: David Ronk <david@expectedbehavior.com>

Co-authored-by: David Ronk <david@expectedbehavior.com>

Author: AlexOverbeck

_sections/30-projects.md

@@ -112,6 +112,7 @@ These projects pledge to drop Python 2 support in or before 2020.
 - [![](assets/platon.png)PLATON](https://github.com/ideasrule/platon) <!-- url:https://github.com/ideasrule/platon sg:5 -->
 - [![](https://raw.githubusercontent.com/GeoStat-Framework/GSTools/master/docs/source/pics/gstools.png)GSTools](https://github.com/GeoStat-Framework/GSTools) <!-- url:https://github.com/GeoStat-Framework/GSTools sg:38 -->
 - [![](assets/cantor.png)Cantor](https://cantor.kde.org)
+- [![](assets/docraptor.svg)DocRaptor](https://docraptor.com) <!-- url:https://github.com/DocRaptor/docraptor-python sg:12 -->
 
 <!-- Adding a new project with a logo? They're roughly sorted by GitHub stars.
 Try to insert yours in order. We use judgment for projects not on GiHhub, and