Add google/pull/3173 in CHANGELOG.md

CHANGELOG.md

@@ -9,10 +9,18 @@
     different version can lead to presubmits failing due to unexpected
     diffs.
 
+### Storage
+
+#### MySQL
+
+* mysql: check for error when getting subtrees by @jsha in https://github.com/google/trillian/pull/3173
+
 ### Documentation
+
 * Added comments to show how snippets were generated by @mhutchinson in https://github.com/google/trillian/pull/3048
 
 ### Misc
+
 * Export logserver read counter metric together with logIDs by @phbnf in https://github.com/google/trillian/pull/3077
 * Register DoFns by @AlCutter in https://github.com/google/trillian/pull/3083
 * Add docker package-ecosystem to Dependabot config by @roger2hk in https://github.com/google/trillian/pull/3038
@@ -26,6 +34,7 @@
 * Add top level read-only permission in govulncheck.yml by @roger2hk in https://github.com/google/trillian/pull/3092
 
 ### Dependency updates
+
 * Bump go.etcd.io/etcd/etcdctl/v3 from 3.5.8 to 3.5.9 by @dependabot in https://github.com/google/trillian/pull/3003
 * Bump google.golang.org/api from 0.121.0 to 0.122.0 by @dependabot in https://github.com/google/trillian/pull/3006
 * Bump golang.org/x/tools from 0.8.0 to 0.9.1 by @dependabot in https://github.com/google/trillian/pull/3005