Documentation improvements for OffsetDateTime.
Documentation improvements for OffsetDateTime.

malcolmr/nodatime,jskeet/nodatime,BenJenkinson/nodatime,zaccharles/nodatime,zaccharles/nodatime,zaccharles/nodatime,nodatime/nodatime,jskeet/nodatime,BenJenkinson/nodatime,nodatime/nodatime,malcolmr/nodatime,zaccharles/nodatime,zaccharles/nodatime,malcolmr/nodatime,malcolmr/nodatime,zaccharles/nodatime