GPencil: Change UI text and tooltip

The text was not changed in the refactor and had the old text.

source/blender/makesrna/intern/rna_gpencil.c

@@ -2197,7 +2197,10 @@ static void rna_def_gpencil_layer(BlenderRNA *brna)
 
   prop = RNA_def_property(srna, "use_mask_layer", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_sdna(prop, NULL, "flag", GP_LAYER_USE_MASK);
-  RNA_def_property_ui_text(prop, "Mask Layer", "Mask pixels from underlying layers drawing");
+  RNA_def_property_ui_text(
+      prop,
+      "Use Mask",
+      "The visibility of drawings on this layer is affected by the layers in its masks list");
   RNA_def_property_update(prop, NC_GPENCIL | ND_DATA, "rna_GPencil_update");
 
   prop = RNA_def_property(srna, "use_lights", PROP_BOOLEAN, PROP_NONE);