Fix submodule ref

Aaron1011 · Aaron1011 · commit 87881799a20e · 2018-02-18T19:40:13.000-05:00
diff --git a/src/doc/rust-by-example b/src/doc/rust-by-example
@@ -1 +1 @@
-Subproject commit 919980be7df4ea7d45a9dca8efc34da89bcf7d6b
+Subproject commit ebb28c95b2ea68b96eddb9e71aff4d32eacc74f0
