add release notes (#119) #369

Job	Run time
Checks	2m 28s
Compile Benchmarks	1m 27s
Docs	2m 19s
Compile and test (2.12, 8)	4m 6s
Compile and test (2.12, 11)	5m 21s
Compile and test (2.13, 8)	4m 38s
Compile and test (2.13, 11)	5m 14s
Compile and test (3.3, 8)	5m 2s
Compile and test (3.3, 11)	5m 58s
Gradle tests	3m 38s
Maven tests	2m 59s
sbt scripted tests (gen-scala-server, 2.12)	9m 17s
sbt scripted tests (gen-java, 2.12)	3m 41s
	56m 8s

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