New Sidebar and restructuring

Changes

• Fixes sidebar on mobile (90%)
• Introduces new mechanism for TOC on mobile & larger displays (90%)
• Moves configuration files to configs/
• Fixes sitemap URL in templates/robots.txt
• Proofreading for kyu 7
• Move Gürtel.md to tracking issue (#9)
• Will introduce rudimentary docker-compose script (70%) (Moved to #10 (closed))
• Add templates for issues and merge requests (Will most likely be moved to own issue)

CC: @bengoshi for proofreading of content