fix(strings): Correct capitalization of a string

Author: chsbuffer

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

@@ -2,7 +2,7 @@
     <string name="app_name">ReVanced Xposed</string>
     <string name="app_description">ReVanced Xposed</string>
     <string name="app_launcher_name">PLACEHOLDER</string>
-    <string name="check_for_update_title">Check for Update</string>
+    <string name="check_for_update_title">Check for update</string>
     <string name="patch_selection">Patch Selection</string>
     <string name="force_stop_to_apply_summary">Force stop the corresponding application to apply the settings.</string>
     <string name="about_title">About</string>