go: add «2486. Append Characters to String to Make Subsequence»

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

go/append-characters-to-string-to-make-subsequence.go

@@ -0,0 +1,14 @@
+package append_characters_to_string_to_make_subsequence
+
+func appendCharacters(s string, t string) int {
+	si, ti := 0, 0
+
+	for si < len(s) && ti < len(t) {
+		if s[si] == t[ti] {
+			ti++
+		}
+		si++
+	}
+
+	return len(t) - ti
+}