[css-gaps-1][editorial] Add Acknowledgements section

Author: kbabbitt

css-gaps-1/Overview.bs

@@ -1199,6 +1199,28 @@ Security Considerations</h2>
 
 No new security considerations have been reported on this specification.
 
+<h2 id="acknowledgements">
+Acknowledgements</h2>
+
+<p>This specification is made possible by contributions and feedback from many people, including:
+	Ahmad Shadeed,
+	Alison Maher,
+	Benoît Rouleau,
+	Elika Etemad,
+	Ian Kilpatrick,
+	Javier Contreras Tenorio,
+	Josh Tumath,
+	Kurt Catti-Schmidt,
+	Lea Verou,
+	Oliver Williams,
+	Rachel Andrew,
+	Sam Davis Omekara Jr.,
+	Sebastian Zartner,
+	Tab Atkins-Bittner,
+	and the CSS Working Group members.
+	Special thanks to Mats Palmgren who drafted an initial proposal for Gap Decorations.
+</p>
+
 <h2 id="changes">
 Changes</h2>