[codespell] Adding Tox Target for Codespell

First in a series of commits to add Codespell to Ironic Repos. This one adds the command that was used to fix the spelling errors.

Future Commits will add CI support and potentially a git-blame-ignore-revs file if their are lots of spelling mistakes that could clutter git blame.

Change-Id: Ibeb4cd8bd38e6bfe04adb8ce66ce36f30f06eb61

setup.cfg

@@ -34,3 +34,8 @@ data_files =
 [entry_points]
 console_scripts =
     metalsmith = metalsmith._cmd:main
+
+[codespell]
+quiet-level = 4
+# Words to ignore:
+# ignore-words-list = example

tox.ini

@@ -17,7 +17,7 @@ deps =
     -r{toxinidir}/test-requirements.txt
 commands =
     stestr run {posargs}
-passenv = 
+passenv =
     http_proxy
     HTTP_PROXY
     https_proxy
@@ -119,3 +119,12 @@ deps =
   ansible-lint>=5,<6
 commands =
     bash tools/ansible-lint.sh
+
+[testenv:codespell]
+description =
+  Run codespell to check spelling
+deps = codespell
+# note(JayF): {posargs} lets us run `tox -ecodespell -- -w` to get codespell
+#             to correct spelling issues in our code it's aware of.
+commands =
+  codespell {posargs}