Add preference to allow hiding release notes on upgrade/install

defaults/preferences/prefs.js

@@ -2,3 +2,4 @@ pref('extensions.jid1-BoFifL9Vbdl2zQ@jetpack.addNotice', true);
 pref('extensions.jid1-BoFifL9Vbdl2zQ@jetpack.blockMissing', false);
 pref('extensions.jid1-BoFifL9Vbdl2zQ@jetpack.domainWhitelist', '');
 pref('extensions.jid1-BoFifL9Vbdl2zQ@jetpack.amountInjected', 0);
+pref('extensions.jid1-BoFifL9Vbdl2zQ@jetpack.showReleaseNotes', true);

lib/main.js

@@ -33,7 +33,7 @@ exports.main = function (options) {
     // Initialize add-on state.
     interceptor.register();
 
-    if (options.loadReason === 'install' || options.loadReason === 'upgrade') {
+    if (preferences.showReleaseNotes && (options.loadReason === 'install' || options.loadReason === 'upgrade')) {
 
         if (preferences['sdk.baseURI']) {
             tabs.open(preferences['sdk.baseURI'] + 'static/release-notes.html');