Change a hardcoded string to a translatable message (commons-app#6444)

Follow-up to commons-app#6443. Noticed this one after that pull request
was already merged.

Author: amire80

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

@@ -154,6 +154,7 @@
   <string name="navigation_item_notification">{{Identical|Notification}}</string>
   <string name="navigation_item_review">{{Identical|Review}}</string>
   <string name="upload_connection_error_alert_title">{{Identical/Connection Error}}</string>
+  <string name="preferences_uploads">A section title in preferences.</string>
   <string name="nominated_see_more">&lt;u&gt;See webpage for details&lt;/u&gt;</string>
   <string name="skip_login">{{Identical|Skip}}</string>
   <string name="navigation_item_login">{{Identical|Log in}}</string>

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

@@ -269,6 +269,7 @@
 
   <string name="upload_problem_image">Problems found in image</string>
   <string name="internet_downloaded">Please only upload pictures that you have taken by yourself. Don\'t upload pictures that you have downloaded from the Internet.</string>
+  <string name="preferences_uploads">Uploads</string>
   <string name="use_external_storage">Save In-app shots</string>
   <string name="use_external_storage_summary">Save pictures taken with the in-app camera to your device storage</string>
   <string name="login_to_your_account">Log in to your account</string>

app/src/main/res/xml/preferences.xml

@@ -61,7 +61,7 @@
     </PreferenceCategory>
 
     <PreferenceCategory
-        android:title="Uploads">
+        android:title="@string/preferences_uploads">
 
         <SwitchPreference