update release notes with more about plugin API changes
update release notes with more about plugin API changes

GMOD/jbrowse,nathandunn/jbrowse,GMOD/jbrowse,GMOD/jbrowse,GMOD/jbrowse,nathandunn/jbrowse,GMOD/jbrowse,nathandunn/jbrowse,nathandunn/jbrowse,nathandunn/jbrowse