feat: add swift implementation to lcci problem: No.08.05 (doocs#2687)

Author: klever34

lcci/08.05.Recursive Mulitply/README.md

@@ -110,6 +110,20 @@ impl Solution {
 }
 ```
 
+```swift
+class Solution {
+    func multiply(_ A: Int, _ B: Int) -> Int {
+        if B == 1 {
+            return A
+        }
+        if (B & 1) == 1 {
+            return (multiply(A, B >> 1) << 1) + A
+        }
+        return multiply(A, B >> 1) << 1
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- end -->

lcci/08.05.Recursive Mulitply/README_EN.md

@@ -115,6 +115,20 @@ impl Solution {
 }
 ```
 
+```swift
+class Solution {
+    func multiply(_ A: Int, _ B: Int) -> Int {
+        if B == 1 {
+            return A
+        }
+        if (B & 1) == 1 {
+            return (multiply(A, B >> 1) << 1) + A
+        }
+        return multiply(A, B >> 1) << 1
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- end -->

lcci/08.05.Recursive Mulitply/Solution.swift

@@ -0,0 +1,11 @@
+class Solution {
+    func multiply(_ A: Int, _ B: Int) -> Int {
+        if B == 1 {
+            return A
+        }
+        if (B & 1) == 1 {
+            return (multiply(A, B >> 1) << 1) + A
+        }
+        return multiply(A, B >> 1) << 1
+    }
+}