DOC previous versions -> all available versions (scikit-learn#10178)

Author: qinhanmin2014

doc/documentation.rst

@@ -30,7 +30,7 @@ Documentation of scikit-learn |version|
                     <ul>
                         <script>if (VERSION_SUBDIR != "stable") document.write('<li><a href="http://scikit-learn.org/stable/documentation.html">Stable version</a></li>')</script>
                         <script>if (VERSION_SUBDIR != "dev") document.write('<li><a href="http://scikit-learn.org/dev/documentation.html">Development version</a></li>')</script>
-                        <li><a href="http://scikit-learn.org/dev/versions.html">Previous versions</a></li>
+                        <li><a href="http://scikit-learn.org/dev/versions.html">All available versions</a></li>
                         <li><a href="_downloads/scikit-learn-docs.pdf">PDF documentation</a></li>
                     </ul>
 

doc/themes/scikit-learn/layout.html

@@ -92,7 +92,7 @@
             <li class="divider"></li>
                 <script>if (VERSION_SUBDIR != "stable") document.write('<li><a href="http://scikit-learn.org/stable/documentation.html">Stable version</a></li>')</script>
                 <script>if (VERSION_SUBDIR != "dev") document.write('<li><a href="http://scikit-learn.org/dev/documentation.html">Development version</a></li>')</script>
-                <li><a href="http://scikit-learn.org/dev/versions.html">Previous versions</a></li>
+                <li><a href="http://scikit-learn.org/dev/versions.html">All available versions</a></li>
                 <li><a href="{{ pathto('_downloads/scikit-learn-docs.pdf', 1) }}">PDF documentation</a></li>
               </ul>
             </div>