Update whatsnew (SciTools#4924)

* reset whatsnew

* remove bugfix section

* address review comments

docs/src/whatsnew/index.rst

@@ -5,12 +5,13 @@
 What's New in Iris
 ------------------
 
-.. include:: 3.3.rst
+.. include:: latest.rst
 
 .. toctree::
    :maxdepth: 1
    :hidden:
 
+   latest.rst
    3.3.rst
    3.2.rst
    3.1.rst

docs/src/whatsnew/latest.rst

@@ -0,0 +1,89 @@
+.. include:: ../common_links.inc
+
+|iris_version| |build_date| [unreleased]
+****************************************
+
+This document explains the changes made to Iris for this release
+(:doc:`View all changes <index>`.)
+
+
+.. dropdown:: :opticon:`report` |iris_version| Release Highlights
+   :container: + shadow
+   :title: text-primary text-center font-weight-bold
+   :body: bg-light
+   :animate: fade-in
+   :open:
+
+   The highlights for this major/minor release of Iris include:
+
+   * N/A
+
+   And finally, get in touch with us on :issue:`GitHub<new/choose>` if you have
+   any issues or feature requests for improving Iris. Enjoy!
+
+
+📢 Announcements
+================
+
+#. N/A
+
+
+✨ Features
+===========
+
+#. N/A
+
+
+🐛 Bugs Fixed
+=============
+
+#. N/A
+
+
+💣 Incompatible Changes
+=======================
+
+#. N/A
+
+
+🚀 Performance Enhancements
+===========================
+
+#. N/A
+
+
+🔥 Deprecations
+===============
+
+#. N/A
+
+
+🔗 Dependencies
+===============
+
+#. N/A
+
+
+📚 Documentation
+================
+
+#. N/A
+
+
+💼 Internal
+===========
+
+#. N/A
+
+
+.. comment
+    Whatsnew author names (@github name) in alphabetical order. Note that,
+    core dev names are automatically included by the common_links.inc:
+
+
+
+
+.. comment
+    Whatsnew resources in alphabetical order:
+
+