Bug 1458668 - Link CHANGELOG.md in javadoc. r=snorp,geckoview-reviewers

This moves the CHANGELOG.md file to a /doc-files folder that gets picked up by
javadoc.

Our javadoc files are hosted on a github.io page which will render the markdown
file with the geckoview profile.

Depends on D13883

Differential Revision: https://phabricator.services.mozilla.com/D14786

--HG--
rename : mobile/android/geckoview/CHANGELOG.md => mobile/android/geckoview/src/main/java/org/mozilla/geckoview/doc-files/CHANGELOG.md
extra : moz-landing-system : lando

mobile/android/geckoview/build.gradle

@@ -496,6 +496,6 @@ apply plugin: 'org.mozilla.apilint'
 apiLint {
     // TODO: Change this to `org` after hiding org.mozilla.gecko
     packageFilter = 'org.mozilla.geckoview'
-    changelogFileName = 'CHANGELOG.md'
+    changelogFileName = 'src/main/java/org/mozilla/geckoview/doc-files/CHANGELOG.md'
     lintFilters = ['GV']
 }

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

@@ -1,4 +1,10 @@
-# v65
+---
+layout: geckoview
+---
+
+<h1> GeckoView API Changelog. </h1>
+
+## v65
 - Moved `CompositorController`, `DynamicToolbarAnimator`,
   `OverscrollEdgeEffect`, `PanZoomController` from `org.mozilla.gecko.gfx` to
   `org.mozilla.geckoview`

mobile/android/geckoview/src/main/java/org/mozilla/geckoview/package-info.java

@@ -43,5 +43,6 @@
  *     <li>{@link android.Manifest.permission#RECORD_AUDIO}</li>
  * </ul>
  *
+ * For a detailed change log of the API see: <a href="./doc-files/CHANGELOG">CHANGELOG</a>.
  */
 package org.mozilla.geckoview;