initially convert original docx to rst

[Nils-Magnus]

• converted the original docx document with Pandoc
• split document into main parts
• discarded the initial tables and toc that may get autogenerated later on
• rephrased the main page index.rst
• linked the main parts from the main page

[otc-zuul[bot]]

Build succeeded. https://zuul.otc-service.com/t/eco/buildset/b801076d86834681bb5c24e6138008e9

:heavy_check_mark: noop SUCCESS in 0s :heavy_check_mark: otc-tox-docs SUCCESS in 4m 26s :heavy_check_mark: build-otc-umn SUCCESS in 2m 04s