Use the grammatically correct variant of the indefinite article

Author: victoryforce

src/iop/sigmoid.c

@@ -1,6 +1,6 @@
 /*
     This file is part of darktable,
-    Copyright (C) 2020-2024 darktable developers.
+    Copyright (C) 2020-2025 darktable developers.
 
     darktable is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -199,7 +199,7 @@ const char *aliases()
 const char **description(dt_iop_module_t *self)
 {
   return dt_iop_set_description(self,
-                                _("apply a view transform to make a image displayable\n"
+                                _("apply a view transform to make an image displayable\n"
                                   "on a screen or print. uses a robust and smooth\n"
                                   "tone curve with optional color preservation methods."),
                                 _("corrective and creative"), _("linear, RGB, scene-referred"),