Add a CREDITS file

  We've already had a lot of help, let's give them credit.
  It's a nice thing to do... and perhaps it'll encourage more help.

Signed-off-by: David A. Wheeler <dwheeler@dwheeler.com>

CREDITS

@@ -0,0 +1,31 @@
+We gratefully acknowledge all those who reviewed or helped develop the
+badging criteria and/or the software to implement it.
+That includes everyone who provided comments via the mailing list,
+issue tracker, or via pull requests.
+
+Alphabetically by last name, contributors include:
+Mark Atwood
+Tod Beardsley
+Doug Birdwell
+Alton(ius) Blom
+Hanno Böck
+enos-dandrea
+David Drysdale
+Karl Fogel
+Alex Jordan (strugee)
+Sam Khakimov
+Greg Kroah-Hartman
+Dan Kohn
+Charles Neill (cneill)
+Emily Ratliff
+Tom Ritter
+Trevor Vaughan
+Florian Weimer
+David A. Wheeler
+
+(Apologies in advance for anyone we've accidentally omitted.)
+
+Karl Fogel not only provided us helpful inputs, but his book
+"Producing Open Secure Software" <http://producingoss.com/>
+was an important basis for identifying many project best practices - thank you!
+