Update sign in wording on the SDK (#4168)

* Update sign in wording on the SDK

Author: tejasd

firebase-appdistribution/src/main/res/values/strings.xml

@@ -14,8 +14,8 @@
 
 <resources>
 
-  <string name="signin_dialog_title">Enable new build alerts</string>
-  <string name="singin_dialog_message">Get in-app alerts when new builds are ready to test.</string>
+  <string name="signin_dialog_title">Enable testing features</string>
+  <string name="singin_dialog_message">Enable testing features like new build alerts and in-app feedback.</string>
   <string name="singin_yes_button">Turn on</string>
   <string name="singin_no_button">Not now</string>
   <string name="no_update_available">No new release available, try calling checkForUpdate.</string>