Remove ALPHA from dual page split label

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

@@ -254,7 +254,7 @@
     <string name="pref_fullscreen">Fullscreen</string>
     <string name="pref_show_navigation_mode">Show navigation layout overlay</string>
     <string name="pref_show_navigation_mode_summary">Briefly show tap zones when reader is opened</string>
-    <string name="pref_dual_page_split">Dual page split (ALPHA)</string>
+    <string name="pref_dual_page_split">Dual page split</string>
     <string name="pref_dual_page_invert">Invert dual page split placement</string>
     <string name="pref_dual_page_invert_summary">If the placement of the dual page split doesn\'t match reading direction</string>
     <string name="pref_cutout_short">Show content in cutout area</string>