PyDoc: Improve description of texture.evaluate

Inspired by the old 2.49 docs: https://docs.blender.org/api/249PythonDoc/Texture.Texture-class.html#evaluate

source/blender/makesrna/intern/rna_texture_api.c

@@ -61,12 +61,30 @@ void RNA_api_texture(StructRNA *srna)
   func = RNA_def_function(srna, "evaluate", "texture_evaluate");
   RNA_def_function_ui_description(func, "Evaluate the texture at the coordinates given");
 
-  parm = RNA_def_float_vector(func, "value", 3, NULL, -FLT_MAX, FLT_MAX, "", "", -1e4, 1e4);
+  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);
   RNA_def_parameter_flags(parm, 0, PARM_REQUIRED);
-
   /* return location and normal */
   parm = RNA_def_float_vector(
-      func, "result", 4, NULL, -FLT_MAX, FLT_MAX, "Result", NULL, -1e4, 1e4);
+      func,
+      "result",
+      4,
+      NULL,
+      -FLT_MAX,
+      FLT_MAX,
+      "The result of the texture where (x,y,z,w) are (red, green, blue, intensity). For greyscale "
+      "textures, often intensity only will be used",
+      NULL,
+      -1e4,
+      1e4);
   RNA_def_parameter_flags(parm, PROP_THICK_WRAP, 0);
   RNA_def_function_output(func, parm);
 }