add content description to add reaction button (#2838)

app/src/main/res/layout/item_announcement.xml

@@ -20,8 +20,8 @@
         android:layout_width="0dp"
         android:layout_height="wrap_content"
         android:padding="8dp"
-        app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toBottomOf="@id/text">
 
         <com.google.android.material.chip.Chip
@@ -30,6 +30,7 @@
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:checkable="false"
+            android:contentDescription="@string/action_add_reaction"
             app:chipEndPadding="4dp"
             app:chipIcon="@drawable/ic_plus_24dp"
             app:chipSurfaceColor="@color/tusky_blue"

app/src/main/res/values/strings.xml

@@ -153,6 +153,7 @@
     <string name="action_open_faved_by">Show favorites</string>
     <string name="action_dismiss">Dismiss</string>
     <string name="action_details">Details</string>
+    <string name="action_add_reaction">add reaction</string>
 
     <string name="title_hashtags_dialog">Hashtags</string>
     <string name="title_mentions_dialog">Mentions</string>