PUBDEV-4396: GLM documentation updates (#1108)
PUBDEV-4396: GLM documentation updates (#1108)

GLM can now supports multinomial classification models.
Driveby: For PUBDEV-4258, added two FAQs to the GLM topic describing
why H2O’s glm differs from R’s and how to get the two to match.
spennihana/h2o-3,h2oai/h2o-3,h2oai/h2o-3,spennihana/h2o-3,mathemage/h2o-3,mathemage/h2o-3,h2oai/h2o-3,h2oai/h2o-dev,h2oai/h2o-3,spennihana/h2o-3,michalkurka/h2o-3,michalkurka/h2o-3,mathemage/h2o-3,h2oai/h2o-dev,h2oai/h2o-dev,h2oai/h2o-dev,h2oai/h2o-3,h2oai/h2o-dev,h2oai/h2o-3,mathemage/h2o-3,spennihana/h2o-3,mathemage/h2o-3,h2oai/h2o-3,michalkurka/h2o-3,spennihana/h2o-3,mathemage/h2o-3,spennihana/h2o-3,michalkurka/h2o-3,mathemage/h2o-3,michalkurka/h2o-3,h2oai/h2o-dev,michalkurka/h2o-3,spennihana/h2o-3,h2oai/h2o-dev,h2oai/h2o-3,michalkurka/h2o-3