Add release notes for full/right outer join

presto-docs/src/main/sphinx/release/release-0.102.rst

@@ -15,6 +15,17 @@ Additionally, the functions operate on Unicode code points and not user visible
 into a single user-perceived *character*, the basic unit of a writing system for a
 language, but the functions will treat each code point as a separate unit.
 
+Full and Right Outer Join
+-------------------------
+
+Execution of right outer joins has changed. Right joins are no longer flipped
+and executed as left outer joins. Instead, they are hash partitioned. For each
+partition, an index is built on the right side. Left side is used to probe the
+index to produce the inner join result. At the end, unvisited index entries are
+processed to produce additional rows in the result.
+
+Full outer join support has also been added. It is executed in a way that
+combines how left joins and right joins are executed.
 
 General Changes
 ---------------