docs/index: Reorder contribution guide order

It should go last in the list of topics, preceding only
the API docs.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
docs: Updating test references

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
docs: Update env variables documentation

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
Merge pull request #209 from lmr/docs-update

Docs update