Update affiliation for Master page and readme file and indicate that it is SWMM 5.1.014

[michelleannesimon]

Please update affiliation in the Readme file, Introduction, and elsewhere for the Master link as well: Also indicate that the master and develop are from SWMM 5.1.014.

“This is the official SWMM source code repository maintained by US EPA ORD, NRMRL, Water Supply and Water Resources Division located in Cincinnati, Ohio.”

To “This is the official SWMM source code repository maintained by US EPA Office of Research and Development, Center For Environmental Solutions & Emergency Response, Water Infrastructure Division located in Cincinnati, Ohio.”