Start 1.4 changelog and release notes

CHANGELOG.txt

@@ -1,6 +1,9 @@
 Changelog
 =========
 
+1.4 (xx.xx.xxxx)
+~~~~~~~~~~~~~~~~
+
 1.3 (xx.xx.xxxx)
 ~~~~~~~~~~~~~~~~
 

docs/releases/1.4.rst

@@ -0,0 +1,20 @@
+==========================================
+Wagtail 1.4 release notes - IN DEVELOPMENT
+==========================================
+
+.. contents::
+    :local:
+    :depth: 1
+
+
+What's new
+==========
+
+Minor features
+~~~~~~~~~~~~~~
+
+Bug fixes
+~~~~~~~~~
+
+Upgrade considerations
+======================

docs/releases/index.rst

@@ -4,6 +4,7 @@ Release notes
 .. toctree::
    :maxdepth: 1
 
+   1.4
    1.3
    1.2
    1.1