Update release_notes.txt

Address Serdar's review comments in closed PR

Fix compilation error after IMDG update (hazelcast#2137)

Unify various trade sources, extract in separate module (hazelcast#2013)

Change packaging of refman to pom

3.2.2

3.2.1-adobe

Add release notes

Fix javadoc for Assertions

Fixes hazelcast#1672

Add release notes and changelog (hazelcast#1450)