Added release notes for 3.20.0.10
Added release notes for 3.20.0.10

michalkurka/h2o-3,michalkurka/h2o-3,michalkurka/h2o-3,h2oai/h2o-dev,h2oai/h2o-dev,michalkurka/h2o-3,h2oai/h2o-dev,h2oai/h2o-3,michalkurka/h2o-3,h2oai/h2o-3,h2oai/h2o-3,h2oai/h2o-3,h2oai/h2o-dev,h2oai/h2o-3,h2oai/h2o-dev,h2oai/h2o-3,michalkurka/h2o-3,h2oai/h2o-3,h2oai/h2o-dev,michalkurka/h2o-3,h2oai/h2o-dev,h2oai/h2o-3