Updated read_length description. Added comment to read_length_units to state that by default nt value is assigned by server.
Updated read_length description. Added comment to read_length_units to state that by default nt value is assigned by server.

T2DREAM/t2dream-portal,ClinGen/clincoded,philiptzou/clincoded,ClinGen/clincoded,kidaa/encoded,philiptzou/clincoded,hms-dbmi/fourfront,philiptzou/clincoded,4dn-dcic/fourfront,hms-dbmi/fourfront,T2DREAM/t2dream-portal,kidaa/encoded,ClinGen/clincoded,4dn-dcic/fourfront,hms-dbmi/fourfront,ENCODE-DCC/snovault,philiptzou/clincoded,ENCODE-DCC/snovault,T2DREAM/t2dream-portal,kidaa/encoded,T2DREAM/t2dream-portal,ENCODE-DCC/encoded,ENCODE-DCC/snovault,ENCODE-DCC/encoded,ClinGen/clincoded,philiptzou/clincoded,kidaa/encoded,ENCODE-DCC/encoded,ENCODE-DCC/snovault,4dn-dcic/fourfront,4dn-dcic/fourfront,hms-dbmi/fourfront,ENCODE-DCC/encoded,ClinGen/clincoded,kidaa/encoded,hms-dbmi/fourfront,ENCODE-DCC/snovault