Update history doc to add breaking changes
diff --git a/site/_docs/history.md b/site/_docs/history.md
index f21942f..c9196d5 100644
--- a/site/_docs/history.md
+++ b/site/_docs/history.md
@@ -36,6 +36,10 @@
Mark `CalcMergeRule` as `TransformationRule`
* [<a href="https://issues.apache.org/jira/browse/CALCITE-4003">CALCITE-4003</a>]
Disallow cross convention matching and `PhysicalNode` generation in `TransformationRule`
+* [<a href="https://issues.apache.org/jira/browse/CALCITE-3786">CALCITE-3786</a>]
+ Change `RelNode#recomputeDigest()` return type from `String` to `void`. To get
+ digest string, use `RelNode#getDigest()` instead, it will create new digest
+ string on each call, so don't forget to cache the result if necessary
## <a href="https://github.com/apache/calcite/releases/tag/calcite-1.23.0">1.23.0</a> / 2020-05-23
{: #v1-23-0}
