[gimp] plug-ins: clearer plug-in-screenshot parameter description.

[Jehan <jehanp src gnome org>]

commit 3a0c03a61ceec273a69c1ac0c766bfe0c5c6bb1e
Author: Jehan <jehan girinstud io>
Date:   Sun Jun 17 22:11:26 2018 +0200

    plug-ins: clearer plug-in-screenshot parameter description.
    
    Our plug-ins have no "optional" parameters per-se. Clarify the
    description to make explicit that the last 4 parameters are simply only
    taken into account when the shoot type is SHOOT-REGION.

 plug-ins/screenshot/screenshot.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/plug-ins/screenshot/screenshot.c b/plug-ins/screenshot/screenshot.c
index e2c81ed74a..c99ad01c04 100644
--- a/plug-ins/screenshot/screenshot.c
+++ b/plug-ins/screenshot/screenshot.c
@@ -112,10 +112,10 @@ query (void)
     { GIMP_PDB_INT32, "run-mode",   "The run mode { RUN-INTERACTIVE (0), RUN-NONINTERACTIVE (1) }"     },
     { GIMP_PDB_INT32, "shoot-type", "The Shoot type { SHOOT-WINDOW (0), SHOOT-ROOT (1), SHOOT-REGION (2) }" 
},
     { GIMP_PDB_INT32, "window-id",  "Window id for SHOOT-WINDOW"       },
-    { GIMP_PDB_INT32, "x1",         "(optional) Region left x coord"   },
-    { GIMP_PDB_INT32, "y1",         "(optional) Region top y coord"    },
-    { GIMP_PDB_INT32, "x2",         "(optional) Region right x coord"  },
-    { GIMP_PDB_INT32, "y2",         "(optional) Region bottom y coord" }
+    { GIMP_PDB_INT32, "x1",         "Region left x coord for SHOOT-REGION"   },
+    { GIMP_PDB_INT32, "y1",         "Region top y coord for SHOOT-REGION"    },
+    { GIMP_PDB_INT32, "x2",         "Region right x coord for SHOOT-REGION"  },
+    { GIMP_PDB_INT32, "y2",         "Region bottom y coord for SHOOT-REGION" }
   };
 
   static const GimpParamDef return_vals[] =