add template whats new

Author: jessica-mitchell

doc/htmldoc/whats_new/v3.8/index.rst

@@ -0,0 +1,14 @@
+.. _release_3.8:
+
+What's new in NEST 3 8.
+======================
+
+This page contains a summary of important breaking and non-breaking
+changes from NEST 3.7 to NEST 3.8. In addition to the `release notes
+on GitHub <https://github.com/nest/nest-simulator/releases/>`_, this
+page also contains transition information that helps you to update
+your simulation scripts when you come from an older version of NEST.
+
+If you transition from an earlier version, please see our extensive
+:ref:`transition guide from NEST 2.x to 3.0 <refguide_2_3>` and the
+:ref:`list of updates for previous releases in the 3.x series <whats_new>`.