docs: tidy up footer and GitHub link

docs/_templates/github.html

@@ -1,8 +1,4 @@
 <p>
 <br>
-<a class="github-button" href="https://github.com/dw/mitogen" data-size="large" data-show-count="true" aria-label="Star dw/mitogen on GitHub">Star</a>
-</p>
-
-<p>
-<a href="https://github.com/dw/mitogen/">GitHub Repository</a>
+<a class="github-button" href="https://github.com/dw/mitogen/" data-size="large" data-show-count="true" aria-label="Star dw/mitogen on GitHub">Star</a>
 </p>

docs/conf.py

@@ -18,6 +18,7 @@ html_theme_options = {
     'font_family': "Georgia, serif",
     'head_font_family': "Georgia, serif",
     'fixed_sidebar': True,
+    'show_powered_by': False,
 }
 htmlhelp_basename = 'mitogendoc'
 intersphinx_mapping = {'python': ('https://docs.python.org/3', None)}