Added stub release notes for 3.0.4.

docs/releases/3.0.4.txt

@@ -0,0 +1,7 @@
+==========================
+Django 3.0.4 release notes
+==========================
+
+*Expected March 2, 2020*
+
+Django 3.0.4 fixes several bugs in 3.0.3.

docs/releases/index.txt

@@ -32,6 +32,7 @@ versions of the documentation contain the release notes for any later releases.
 .. toctree::
    :maxdepth: 1
 
+   3.0.4
    3.0.3
    3.0.2
    3.0.1