Start translation to brazilian portuguese

pt-br/code/src/mymath/sqrt.go

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+// Example code for Chapter 1.2 from "Build Web Application with Golang"
+// Purpose: Shows how to create a simple package called `mymath`
+// This package must be imported from another go file to run.
+package mymath
+
+func Sqrt(x float64) float64 {
+	z := 0.0
+	for i := 0; i < 1000; i++ {
+		z -= (z*z - x) / (2 * x)
+	}
+	return z
+}