Update README.md (#539)

* Update README.md

* Update README.md

Some section titles were re-named to conform to GitHub guidelines and the OWA info was moved to a CREDITS section.

* Update README.md

Added link to the Community Forum page.

* Replaced OWA copyright with "(see AUTHORS)".

* Update AUTHORS

Copied format used by the OWA-SWMM project.

* Update README.md

The Disclaimer section was edited to reflect that there actually is a "collaborative" connection between USEPA and OWA.

AUTHORS

@@ -1,8 +1,12 @@
 # Authors ordered by first contribution.
-# (Mostly) Generated by tools/update-authors.sh
 
-Lew Rossman <LRossman@cinci.rr.com>
+Authors with Contributions in the Public Domain:
+
+Lewis Rossman <LRossman@cinci.rr.com>
 Michael Tryby <tryby.michael@epa.gov>
+
+Authors with Contributions Subject to Copyright (see LICENSE):
+
 Sam Hatchett <samhatchett@gmail.com>
 Feng Shang <fshang>
 James Uber <jim@citilogics.com>
@@ -19,8 +23,5 @@ Elad Salomons <selad@optiwater.com>
 Maurizio Cingi <mrzcng2@gmail.com>
 Bryant McDonnell <bemcdonnell@gmail.com>
 Angela Marchi <angela.marchi@adelaide.edu.au>
-Lew Rossman <LRossman@cinci.rr.com>
 Markus Sunela <markus.sunela@fluidit.fi>
 Milad Ghiami <milad-ghiami@users.noreply.github.com>
-
-*** some works are in the public domain, all others licensed under terms: see LICENSE