WIP Expand the documentation of COVIDcast signals
WIP Expand the documentation of COVIDcast signals

cmu-delphi/delphi-epidata,cmu-delphi/delphi-epidata,cmu-delphi/delphi-epidata,cmu-delphi/delphi-epidata,cmu-delphi/delphi-epidata,cmu-delphi/delphi-epidata