bpo-33847: Add '@' operator entry to index (GH-7669)

diff --git a/Doc/reference/expressions.rst b/Doc/reference/expressions.rst
index 61bc912..17f1f2c 100644
--- a/Doc/reference/expressions.rst
+++ b/Doc/reference/expressions.rst
@@ -1139,7 +1139,9 @@
 common type and then multiplied together.  In the latter case, sequence
 repetition is performed; a negative repetition factor yields an empty sequence.
 
-.. index:: single: matrix multiplication
+.. index::
+   single: matrix multiplication
+   operator: @
 
 The ``@`` (at) operator is intended to be used for matrix multiplication.  No
 builtin Python types implement this operator.
diff --git a/Misc/NEWS.d/next/Documentation/2018-06-15-14-58-45.bpo-33847.IIDp6t.rst b/Misc/NEWS.d/next/Documentation/2018-06-15-14-58-45.bpo-33847.IIDp6t.rst
new file mode 100644
index 0000000..3c7e0cd
--- /dev/null
+++ b/Misc/NEWS.d/next/Documentation/2018-06-15-14-58-45.bpo-33847.IIDp6t.rst
@@ -0,0 +1 @@
+Add '@' operator entry to index.