Style the headers for release-notes
Style the headers for release-notes

Title level was inconsistent for release notes

Change-Id: I3e8edc04e6bcd77134a43e4543f4255ff49e16d6
Signed-off-by: cristinapauna <2865432cfe3fa410bcf9db1c55e02da5bf19ab9e@enea.com>

opnfv/functest,mywulin/functest,opnfv/functest,mywulin/functest