DOC fix news entry for v1.0 (#21123)

doc/templates/index.html

@@ -155,6 +155,8 @@ <h4 class="sk-landing-call-header">News</h4>
         <ul class="sk-landing-call-list list-unstyled">
         <li><strong>On-going development:</strong>
         <a href="https://scikit-learn.org/dev/whats_new.html"><strong>What's new</strong> (Changelog)</a>
+        <li><strong>September 2021.</strong> scikit-learn 1.0 is available for download (<a href="whats_new/v1.0.html#version-1-0">Changelog</a>).
+        </li>
         <li><strong>April 2021.</strong> scikit-learn 0.24.2 is available for download (<a href="whats_new/v0.24.html#version-0-24-2">Changelog</a>).
         </li>
         <li><strong>January 2021.</strong> scikit-learn 0.24.1 is available for download (<a href="whats_new/v0.24.html#version-0-24-1">Changelog</a>).
@@ -173,12 +175,6 @@ <h4 class="sk-landing-call-header">News</h4>
         <li><strong>January 2020.</strong> scikit-learn 0.22.1 is available for download (<a href="whats_new/v0.22.html#version-0-22-1">Changelog</a>).
         <li><strong>December 2019.</strong> scikit-learn 0.22 is available for download (<a href="whats_new/v0.22.html#version-0-22-0">Changelog</a> and <a href="{{ pathto('auto_examples/release_highlights/plot_release_highlights_0_22_0') }}">Release Highlights</a>).
         </li>
-        <li><strong>Scikit-learn from 0.21 requires Python 3.5 or greater.</strong>
-        </li>
-        <li><strong>July 2019.</strong> scikit-learn 0.21.3 (<a href="whats_new/v0.21.html#version-0-21-3">Changelog</a>) and 0.20.4 (<a href="whats_new/v0.20.html#version-0-20-4">Changelog</a>) are available for download.
-        </li>
-        <li><strong>May 2019.</strong> scikit-learn 0.21.0 to 0.21.2 are available for download (<a href="whats_new/v0.21.html#version-0-21-2">Changelog</a>).
-        </li>
         </ul>
       </div>
       <div class="col-md-4">