Add introduction material on the main documentation page (#3628)

doc/sphinx/source/index.rst

@@ -6,11 +6,30 @@
 Welcome to ESMValTool's documentation!
 ======================================
 
+To get a first impression of what ESMValTool and ESMValCore can do for you,
+have a look at our blog posts
+`Analysis-ready climate data with ESMValCore <https://blog.esciencecenter.nl/easy-ipcc-powered-by-esmvalcore-19a0b6366ea7>`_
+and
+`ESMValTool: Recipes for solid climate science <https://blog.esciencecenter.nl/esmvaltool-recipes-for-solid-climate-science-da5b33814f69>`_.
+
+A tutorial is available on https://tutorial.esmvaltool.org.
+
+A series of video lectures has been created by `ACCESS-NRI <https://access-nri.org.au>`_.
+While these are tailored for ACCESS users, they are still very informative.
+
+.. raw:: html
+
+   <iframe width="560" height="315" src="https://www.youtube.com/embed/videoseries?si=pUXrXB8C8bLRfQHY&amp;list=PLFjfi2xLaFpJp59LvDc1upQsj_xzFlFLc" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
+
+|
+For more detailed information, the documentation is available below.
+
+Get in touch! Contact information is available :ref:`here <Support-and-Contact>`.
+
 .. include:: _sidebar.rst.inc
 
 Indices and tables
 ==================
 
 * :ref:`genindex`
 * :ref:`search`
-