Add 'Cross-Origin problem'

Cross-Origin-problem.md

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+### Cross-Origin problem
+
+Add following values to server response.
+
+* res.header("Access-Control-Allow-Origin", "*");
+* res.header("Access-Control-Allow-Methods", "GET,HEAD,OPTIONS,POST,PUT");
+* res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept, Authorization");