update reference

nikomatsakis · nikomatsakis · commit 775076ff4dc9 · 2019-12-14T15:41:36.000-05:00
diff --git a/src/doc/reference b/src/doc/reference
@@ -1 +1 @@
-Subproject commit 9e843aeb4df083522c7277179bbaa25d0507731c
+Subproject commit d8dfe1b005c03584cd7adc4bfb72b005e7e84744
