DOC Adds release highlights to front page (#17071)

doc/conf.py

@@ -17,6 +17,7 @@
 import warnings
 import re
 from packaging.version import parse
+from pathlib import Path
 
 # If extensions (or modules to document with autodoc) are in another
 # directory, add these directories to sys.path here. If the directory
@@ -208,6 +209,23 @@
 # If true, the reST sources are included in the HTML build as _sources/name.
 html_copy_source = True
 
+# Adds variables into templates
+html_context = {}
+# finds latest release highlights and places it into HTML context for
+# index.html
+release_highlights_dir = Path("..") / "examples" / "release_highlights"
+# Finds the highlight with the latest version number
+latest_highlights = sorted(release_highlights_dir.glob(
+                           "plot_release_highlights_*.py"))[-1]
+latest_highlights = latest_highlights.with_suffix('').name
+html_context["release_highlights"] = \
+    f"auto_examples/release_highlights/{latest_highlights}"
+
+# get version from higlight name assuming highlights have the form
+# plot_release_highlights_0_22_0
+highlight_version = ".".join(latest_highlights.split("_")[-3:-1])
+html_context["release_highlights_version"] = highlight_version
+
 # -- Options for LaTeX output ------------------------------------------------
 latex_elements = {
     # The paper size ('letterpaper' or 'a4paper').

doc/templates/index.html

@@ -8,7 +8,7 @@
         <h1 class="sk-landing-header text-white text-monospace">scikit-learn</h1>
         <h4 class="sk-landing-subheader text-white font-italic mb-3">Machine Learning in Python</h4>
         <a class="btn sk-landing-btn mb-1" href="{{ pathto('getting_started') }}" role="button">Getting Started</a>
-        <a class="btn sk-landing-btn mb-1" href="whats_new/v{{ version }}.html" role="button">What's New in {{ release }}</a>
+        <a class="btn sk-landing-btn mb-1" href="{{ pathto(release_highlights) }}" role="button">Release Highlights for {{ release_highlights_version }}</a>
         <a class="btn sk-landing-btn mb-1" href="https://github.com/scikit-learn/scikit-learn" role="button">GitHub</a>
       </div>
       <div class="col-md-6 d-flex">
@@ -160,7 +160,7 @@ <h4 class="sk-landing-call-header">News</h4>
         </li>
         <li><strong>March 2020.</strong> scikit-learn 0.22.2 is available for download (<a href="whats_new/v0.22.html#version-0-22-2">Changelog</a>).
         <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>).
+        <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>

doc/themes/scikit-learn-modern/nav.html

@@ -9,6 +9,7 @@
 {%- set drop_down_navigation = [
   ('Getting Started', pathto('getting_started')),
   ('Tutorial', pathto('tutorial/index')),
+  ("What's new", 'whats_new/v' + version + '.html'),
   ('Glossary', pathto('glossary')),
   ('Development', pathto('developers/index')),
   ('FAQ', pathto('faq')),