preferences: add specific description for UnifiedPush

Change-Id: Ib22affcc20fefb568e409e826f7aa2980cb5062c

jami-android/app/src/main/res/layout/frag_settings.xml

@@ -560,7 +560,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
                         style="@style/ListSecondary"
                         android:layout_width="match_parent"
                         android:layout_height="wrap_content"
-                        android:text="@string/pref_pushNotifications_summary" />
+                        android:text="@string/pref_pushNotif_summary" />
 
                 </LinearLayout>
 

jami-android/app/src/main/res/values/strings_preferences.xml

@@ -11,7 +11,9 @@
     <string name="pref_mobileData_summary">Allow Jami on 3G/LTE networks additionally to Wi-Fi</string>
 
     <string name="pref_pushNotifications_title">Push notifications</string>
+    <string name="pref_pushNotif_summary" translatable="false" />
     <string name="pref_pushNotifications_summary">Use Google servers to allow receiving calls/messages in the background</string>
+    <string name="pref_unifiedPush_summary">Use a UnifiedPush service to allow receiving calls/messages in the background</string>
 
     <string name="pref_video_advanced_title">Advanced video settings</string>
     <string name="pref_video_advanced_summary">Change the video bitrate, resolution, as well as access experimental features</string>

jami-android/app/src/withFirebase/res/values/strings_preferences.xml

+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+
+    <string name="pref_pushNotif_summary" translatable="false">@string/pref_pushNotifications_summary</string>
+
+</resources>
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jami-android/app/src/withUnifiedPush/res/values/strings_preferences.xml

+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+
+    <string name="pref_pushNotif_summary" translatable="false">@string/pref_unifiedPush_summary</string>
+
+</resources>
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