Function help improvements

resources/function_help/json/decode_uri

@@ -3,10 +3,10 @@
   "type": "function",
   "description": "Takes a layer and decodes the uri of the underlying data provider. It depends on the dataprovider, which data is available.",
   "arguments": [ {"arg":"layer","description":"The layer for which the uri should be decoded."},
-                 {"arg":"part","description":"The part of the uri to return. If unspecified, a map with all uri parts will be returned."} ],
+                 {"arg":"part","description":"The part of the uri to return. If unspecified, a map with all uri parts will be returned.","optional":true} ],
   "examples": [ { "expression":"decode_uri(@layer)", "returns":"{'layerId': '0', 'layerName': '', 'path': '/home/qgis/shapefile.shp'}"},
                 { "expression":"decode_uri(@layer)", "returns":"{'layerId': NULL, 'layerName': 'layer', 'path': '/home/qgis/geopackage.gpkg'}"},
-                { "expression":"decode_uri(@layer), 'path'", "returns":"'C:\my_data\qgis\shape.shp'"}
+                { "expression":"decode_uri(@layer, 'path')", "returns":"'C:\my_data\qgis\shape.shp'"}
               ]
 }