Add list constant and map constant examples

examples/const-and-final/const_and_final.bal

@@ -4,12 +4,18 @@ import ballerina/io;
 const MAX_VALUE = 1000;
 const URL = "https://ballerina.io";
 
+// Map and list can be declared as constant.
+const HTTP_OK = {httpCode: 200, message: "OK"};
+const ERROR_CODES = [200, 202, 400];
+
 // The value for variable `msg` can only be assigned once.
 final string msg = loadMessage();
 
 public function main() {
     io:println(MAX_VALUE);
     io:println(URL);
+    io:println(HTTP_OK);
+    io:println(ERROR_CODES);
     io:println(msg);
 }
 

examples/const-and-final/const_and_final.metatags

@@ -1,2 +1,2 @@
 description: This BBE demonstrates how const and final values are used in Ballerina.
-keywords: ballerina, ballerina by example, bbe, const, final
+keywords: ballerina, ballerina by example, bbe, const, final, map const, list const

examples/const-and-final/const_and_final.out

@@ -1,4 +1,6 @@
 $ bal run const_and_final
 1000
 https://ballerina.io
+{"httpCode":200,"message":"OK"}
+[200,202,400]
 Hello World