Remove Chrome entry for position:sticky from Most Wanted Features list

It's shipping in Chrome 56:
https://bugs.chromium.org/p/chromium/issues/detail?id=231752

[ci skip]

docs/_data/browser-features.yml

@@ -128,16 +128,6 @@
   origin: >
     Bootstrap#19984
 
--
-  browser: >
-    Chrome
-  summary: >
-    Implement [sticky positioning](http://html5please.com/#position:sticky) from CSS Positioned Layout Level 3
-  upstream_bug: >
-    Chromium#231752
-  origin: >
-    Bootstrap#17021
-
 -
   browser: >
     Safari