Bug 1529119 - Remove duplicate entry in CHANGELOG. r=snorp

Differential Revision: https://phabricator.services.mozilla.com/D28238

--HG--
extra : moz-landing-system : lando

mobile/android/geckoview/src/main/java/org/mozilla/geckoview/doc-files/CHANGELOG.md

@@ -90,14 +90,6 @@ exclude: true
 [68.18]: ./WebExtension.html#setMessageDelegate-org.mozilla.geckoview.WebExtension.MessageDelegate-java.lang.String-
 [68.19]: ./WebExtension.Port.html
 
-- Added messaging support for WebExtension. [`setMessageDelegate`][68.17]
-  allows embedders to listen to messages coming from a WebExtension.
-  [`Port`][68.18] allows bidirectional communication between the embedder and
-  the WebExtension.
-
-[68.17]: ./WebExtension.html#setMessageDelegate-org.mozilla.geckoview.WebExtension.MessageDelegate-java.lang.String-
-[68.18]: ./WebExtension.Port.html
-
 ## v67
 - Added [`setAutomaticFontSizeAdjustment`][67.2] to
   [`GeckoRuntimeSettings`][67.3] for automatically adjusting font size settings