The concept of sharing test coverage is not limited to STI. Let's
move it out of the STI section and mention the `tmt` way of
enabling remote repositories as well. Move the `tmt` section up as
it is now the default recommended way how to enable tests. Also
fix typo in the `fedpkg` command used for creating new tests
repositories.
Fix https://pagure.io/fedora-ci/docs/issue/82
Page overview already provided on the right side, no need to
duplicate table of contents in individual pages. Plus added
several changes to fix local docs building. Correct links.
