docs: release notes for the v7.2.11 release

Author: mhevery

CHANGELOG.md

@@ -1,3 +1,10 @@
+<a name="7.2.11"></a>
+## [7.2.11](https://github.com/angular/angular/compare/7.2.10...7.2.11) (2019-03-26)
+
+This release contains various API docs improvements.
+
+
+
 <a name="8.0.0-beta.9"></a>
 # [8.0.0-beta.9](https://github.com/angular/angular/compare/8.0.0-beta.8...8.0.0-beta.9) (2019-03-20)