fix sphinx-lint errors in docs and add ci

This change mainly fixes incorrect use of backticks
but also adress some other minor issues like unbalanced
backticks, incorrect spacing or missing _ in links.

This change add a tox target to run sphinx-lint
as well as adding it to the relevent tox envs to enforce
it in ci. pre-commit is leveraged to install and execute
sphinx-lint but it does not reqiure you to install the
hooks locally into your working dir.

Change-Id: Ib97b35c9014bc31876003cef4362c47a8a3a4e0e

doc/source/user/launch-instance-from-volume.rst

@@ -304,7 +304,7 @@ encryption.
    .. note::
 
       A bootable encrypted volume can also be created by adding the
-      `--type ENCRYPTED_VOLUME_TYPE` parameter to the volume create command.
+      ``--type ENCRYPTED_VOLUME_TYPE`` parameter to the volume create command.
       For example:
 
       .. code-block:: console