Fix a heading in the schema source.
Summary:
Apparently ASCIIdoc doesn't treat something as a heading if its undermark is a
different length than the heading text. Fortunately, there was only one that
had this problem.
Reviewers: #core_team, shahms
@@ -749,7 +749,7 @@ public class E {
[[overridesroot]]
overrides/root
-~~~~~~~~~~~~~~~~~~~~
+~~~~~~~~~~~~~~
Brief description::
A *overrides/root* B if following all *overrides* edges from A would lead to
