feat: add rust solution to lc problem: No.2515 (doocs#1272)

Signed-off-by: xiaolatiao <1628652790@qq.com>

Author: dierbei

solution/2500-2599/2515.Shortest Distance to Target String in a Circular Array/README.md

@@ -198,6 +198,29 @@ impl Solution {
 }
 ```
 
+```rust
+use std::cmp::min;
+
+impl Solution {
+    pub fn closet_target(words: Vec<String>, target: String, start_index: i32) -> i32 {
+        let mut ans = words.len();
+
+        for (i, w) in words.iter().enumerate() {
+            if *w == target {
+                let t = (i as i32 - start_index).abs();
+                ans = min(ans, min(t as usize, words.len() - t as usize));
+            }
+        }
+
+        if ans == words.len() {
+            return -1;
+        }
+
+        ans as i32
+    }
+}
+```
+
 ### **C**
 
 ```c

solution/2500-2599/2515.Shortest Distance to Target String in a Circular Array/README_EN.md

@@ -185,6 +185,29 @@ impl Solution {
 }
 ```
 
+```rust
+use std::cmp::min;
+
+impl Solution {
+    pub fn closet_target(words: Vec<String>, target: String, start_index: i32) -> i32 {
+        let mut ans = words.len();
+
+        for (i, w) in words.iter().enumerate() {
+            if *w == target {
+                let t = (i as i32 - start_index).abs();
+                ans = min(ans, min(t as usize, words.len() - t as usize));
+            }
+        }
+
+        if ans == words.len() {
+            return -1;
+        }
+
+        ans as i32
+    }
+}
+```
+
 ### **C**
 
 ```c