go: add «392. Is Subsequence»

Signed-off-by: Matej Focko <me@mfocko.xyz>

go/is-subsequence.go

@@ -0,0 +1,18 @@
+package main
+
+func isSubsequence(s string, t string) bool {
+	length := len(s)
+
+	i := 0
+	for j := range t {
+		if i < length && t[j] == s[i] {
+			i++
+		}
+
+		if i >= length {
+			break
+		}
+	}
+
+	return i == length
+}