CONTRIBUTING: Update Linux Foundation address in the DCO

With this change, our content matches:

  $ curl http://developercertificate.org/

with the HTML tags removed.

Signed-off-by: W. Trevor King <[email protected]>

Author: wking

CONTRIBUTING.md

@@ -83,8 +83,9 @@ Developer Certificate of Origin
 Version 1.1
 
 Copyright (C) 2004, 2006 The Linux Foundation and its contributors.
-660 York Street, Suite 102,
-San Francisco, CA 94110 USA
+1 Letterman Drive
+Suite D4700
+San Francisco, CA, 94129
 
 Everyone is permitted to copy and distribute verbatim copies of this
 license document, but changing it is not allowed.