Added Go control flow tutorial

Author: Rajeev Kumar Singh

Readme.md

@@ -6,4 +6,6 @@
 
 3. [Golang Basic Types, Operators, and Type Conversion](https://www.callicoder.com/golang-basic-types-operators-type-conversion/)
 
-4. [Working with Constants in Golang](https://www.callicoder.com/golang-typed-untyped-constants/)
+4. [Working with Constants in Golang](https://www.callicoder.com/golang-typed-untyped-constants/)
+
+5. [Golang Control Flow Statements: If, Switch and For](https://www.callicoder.com/golang-control-flow/)