Add release notes for 2.1.3

Conflicts:
	CHANGELOG.txt
	docs/releases/index.rst

CHANGELOG.txt

@@ -44,6 +44,12 @@ Changelog
  * Fix: Fix alignment of checkboxes and radio buttons on Firefox (Matt Westcott)
 
 
+2.1.3 (13.08.2018)
+~~~~~~~~~~~~~~~~~~
+
+ * Fix: Pin Beautiful Soup to 4.6.0 due to further regressions in formatting empty elements (Matt Westcott)
+
+
 2.1.2 (06.08.2018)
 ~~~~~~~~~~~~~~~~~~
 

docs/releases/2.1.3.rst

@@ -0,0 +1,16 @@
+===========================
+Wagtail 2.1.3 release notes
+===========================
+
+.. contents::
+    :local:
+    :depth: 1
+
+
+What's new
+==========
+
+Bug fixes
+~~~~~~~~~
+
+ * Pin Beautiful Soup to 4.6.0 due to further regressions in formatting empty elements (Matt Westcott)

docs/releases/index.rst

@@ -7,6 +7,7 @@ Release notes
    upgrading
    2.3
    2.2
+   2.1.3
    2.1.2
    2.1.1
    2.1