PyDoc: document how parameter are used for 3D and 2D textures

Improves on rB171433e841379e7efad069bbda9880fb271e2fc4

source/blender/makesrna/intern/rna_texture_api.c

@@ -59,19 +59,23 @@ void RNA_api_texture(StructRNA *srna)
   PropertyRNA *parm;
 
   func = RNA_def_function(srna, "evaluate", "texture_evaluate");
-  RNA_def_function_ui_description(func, "Evaluate the texture at the coordinates given");
+  RNA_def_function_ui_description(
+      func, "Evaluate the texture at the a given coordinate and returns the result");
 
-  parm = RNA_def_float_vector(func,
-                              "value",
-                              3,
-                              NULL,
-                              -FLT_MAX,
-                              FLT_MAX,
-                              "The object coordinates (x,y,z) used to generate/map the texture",
-                              "",
-                              -1e4,
-                              1e4);
+  parm = RNA_def_float_vector(
+      func,
+      "value",
+      3,
+      NULL,
+      -FLT_MAX,
+      FLT_MAX,
+      "The coordinates (x,y,z) of the texture, in case of a 3D texture, the z value is the slice "
+      "of the texture that is evaluated. For 2D textures such as images, the z value is ignored",
+      "",
+      -1e4,
+      1e4);
   RNA_def_parameter_flags(parm, 0, PARM_REQUIRED);
+
   /* return location and normal */
   parm = RNA_def_float_vector(
       func,