Inclusive jargon

Following stestr's example where arguments such as --blacklist-file,
--black-regex and --whitelist-file are deprecated since its
3.1.0 release, let's do the change here as well in order to
get tempest consumers some time for the transition.

This change deprecates the following arguments and replaces them
by new ones which are functionally equivavelnt:
* --black-regex is replaced by --exclude-regex
* --blacklist-file is replaced by --exclude-list
* --whitelist-file is replaced by --include-list

For now, Tempest will accept both (new and old) arguments to make
the transition smoother for all consumers.

The patch also bumps min version of tox to 3.18.0 in order to
replace tox's whitelist_externals by allowlist_externals option:
https://github.com/tox-dev/tox/blob/master/docs/changelog.rst#v3180-2020-07-23

Change-Id: I3e09b31f63d2cd7ea41c48e62432bd3bc54fcf44
diff --git a/doc/source/overview.rst b/doc/source/overview.rst
index e51b90b..2eaf72f 100644
--- a/doc/source/overview.rst
+++ b/doc/source/overview.rst
@@ -113,7 +113,7 @@
    There is also the option to use `stestr`_ directly. For example, from
    the workspace dir run::
 
-    $ stestr run --black-regex '\[.*\bslow\b.*\]' '^tempest\.(api|scenario)'
+    $ stestr run --exclude-regex '\[.*\bslow\b.*\]' '^tempest\.(api|scenario)'
 
    will run the same set of tests as the default gate jobs. Or you can
    use `unittest`_ compatible test runners such as `stestr`_, `pytest`_ etc.