Add support for reStructured Text markup language
Created by: Razer6
Support for reStructured Text only needs the python docutils package to be installed.
This PR adds the installation instruction to the install guide and also to the update guide. Because GitLab uses the system python, installation via packet manager is least painful approach to support for docutils
With this PR all *.rst will be rendered as reStructuredText markup language.
This implements feature request http://feedback.gitlab.com/forums/176466-general/suggestions/3868963-add-support-for-restructured-text
/cc @senny as discussed.