Update book and reference submodules

steveklabnik · steveklabnik · commit c0e7b16f61e1 · 2017-03-20T10:10:15.000-04:00
Some links needed adjustment to support this new scheme.
diff --git a/src/doc/book b/src/doc/book
@@ -1 +1 @@
-Subproject commit 979c56634f3fe594c9554c555eee29311d7d4a50
+Subproject commit e6d6caab41471f7115a621029bd428a812c5260e
diff --git a/src/doc/reference b/src/doc/reference
@@ -1 +1 @@
-Subproject commit 2d23ea601f017c106a2303094ee1c57ba856d246
+Subproject commit 516549972d61c8946542d1a34afeae97167ff77b
