documentation: conf: Fix deprecated navigation_with_keys setting bug

[What]

At the current moment, by running the command

`./setup.sh --docs`

we are met with the current error:

  Warning, treated as error:
  The default value for `navigation_with_keys` will change to `False` in
  the next release. If you wish to preserve the old behavior for your
  site, set `navigation_with_keys=True` in the `html_theme_options` dict
  in your `conf.py` file.Be aware that `navigation_with_keys = True` has
  negative accessibility
  implications:pydata/pydata-sphinx-theme#1492

By accessing the link mentioned in the error message, it seems that the
python-sphinx setting `navigation_with_keys` is, by default, set to
`True` and this creates accessibility problems. Thus, the site
compilation fails with the objective of warning users to make a
conscious decision about the setting.

[Why]

Reading the thread from the link, it seems that it is better to set
`navigation_with_keys` to `False`, as the kworkflow site doesn't look to
take advantage of the setting, and we need to make a decision about it.

[How]

Change the `navigation_with_keys` setting to `False` in the
`html_theme_options` Python dictionary of the `documentation/conf.py`
file, as indicated by the error message.

Signed-off-by: David Tadokoro <davidbtadokoro@usp.br>

documentation/conf.py

@@ -97,7 +97,9 @@
 # further.  For a list of options available for each theme, see the
 # documentation.
 #
-# html_theme_options = {}
+html_theme_options = {
+    "navigation_with_keys": False
+}
 
 # Add any paths that contain custom static files (such as style sheets) here,
 # relative to this directory. They are copied after the builtin static files,