Fix #36983 arguments of is_selected are flipped

resources/function_help/json/is_selected

@@ -1,23 +1,25 @@
 {
   "name": "is_selected",
   "type": "function",
-  "description": "Returns if a feature is selected. If called with no parameters checks the current feature.",
-  "arguments": [
+  "description": "Returns True if a feature is selected. Can be used with zero, one or two arguments, see below for details.",
+  "variants": [
         {
-          "arg":"feature",
-          "optional": true,
-          "default": "current feature",
-          "description":"The feature which should be checked for selection."
+            "variant": "No parameters",
+            "variant_description": "If called with no parameters, the function will return true if the current feature in the current layer is selected.",
+            "arguments": [],
+            "examples": [ { "expression": "is_selected()", "returns" : "True if the current feature in the current layer is selected." } ]
         },
         {
-          "arg": "layer",
-          "optional": true,
-          "default": "current layer",
-          "description": "The layer (or its id or name) on which the selection will be checked."
+            "variant": "One 'feature' parameter",
+            "variant_description": "If called with a 'feature' parameter only, the function returns true if the specified feature from the current layer is selected.",
+            "arguments": [ { "arg": "feature", "description": "The feature which should be checked for selection." } ],
+            "examples": [ { "expression": "is_selected(@atlas_feature)", "returns": "True if the current atlas feature is selected." } ]
+        },
+        {
+            "variant" : "Two parameters",
+            "variant_description": "If the function is called with both a layer and a feature, it will return true if the specified feature from the specified layer is selected.",
+            "arguments": [ { "arg": "layer", "description": "The layer (or its ID or name) on which the selection will be checked." }, { "arg": "feature", "description": "The feature which should be checked for selection." } ],
+            "examples": [ { "expression": "is_selected( 'streets', get_feature('streets', 'name', \"street_name\"))", "returns": "True if the current building's street is selected (assuming the building layer has a field named 'street_name' and the 'streets' layer has a field called 'name')." } ]
         }
-  ],
-  "examples": [
-	{ "expression":"is_selected()", "returns" : "True if the current feature is selected."},
-	{ "expression":"is_selected(get_feature('streets', 'name', \"street_name\"), 'streets')", "returns":"True if the current building's street is selected."}
   ]
-}
+ }