Add $env function to JSONata expressions

red/api/editor/locales/en-US/jsonata.json

@@ -190,11 +190,11 @@
     },
     "$flowContext": {
         "args": "string",
-        "desc": "Retrieves a flow context property."
+        "desc": "Retrieves a flow context property.\n\nThis is a Node-RED defined function."
     },
     "$globalContext": {
         "args": "string",
-        "desc": "Retrieves a global context property."
+        "desc": "Retrieves a global context property.\n\nThis is a Node-RED defined function."
     },
     "$pad": {
         "args": "string, width [, char]",
@@ -215,5 +215,9 @@
     "$toMillis": {
         "args": "timestamp",
         "desc": "Convert a `timestamp` string in the ISO 8601 format to the number of milliseconds since the Unix Epoch (1 January, 1970 UTC) as a number. An error is thrown if the string is not in the correct format."
+    },
+    "$env": {
+        "args": "arg",
+        "desc": "Returns the value of an environment variable.\n\nThis is a Node-RED defined function."
     }
 }