Bug 1600671 - Improve doc for onLoadRequest. r=droeh

Differential Revision: https://phabricator.services.mozilla.com/D55696

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

mobile/android/geckoview/src/main/java/org/mozilla/geckoview/GeckoSession.java

@@ -3595,10 +3595,11 @@ public class GeckoSession implements Parcelable {
          * @param session The GeckoSession that initiated the callback.
          * @param request The {@link LoadRequest} containing the request details.
          *
-         * @return A {@link GeckoResult} with a AllowOrDeny value which indicates whether
+         * @return A {@link GeckoResult} with a {@link AllowOrDeny} value which indicates whether
          *         or not the load was handled. If unhandled, Gecko will continue the
-         *         load as normal. If handled (true value), Gecko will abandon the load.
-         *         A null return value is interpreted as false (unhandled).
+         *         load as normal. If handled (a {@link AllowOrDeny#DENY DENY} value), Gecko
+         *         will abandon the load. A null return value is interpreted as
+         *         {@link AllowOrDeny#ALLOW ALLOW} (unhandled).
          */
         @UiThread
         default @Nullable GeckoResult<AllowOrDeny> onLoadRequest(@NonNull GeckoSession session,