docs: add problem description for palindrome partitioning

Author: bujosa

src/medium/readme.md

@@ -689,6 +689,36 @@ Put the code below in main.rs and run `cargo run`
   println!("result: {}", result);
 ```
 
+
+# 131. Palindrome Partitioning
+
+## Description
+
+Given a string s, partition s such that every substring of the partition is a palindrome.
+
+Return all possible palindrome partitioning of s.
+
+## Examples
+
+```text
+Input: "aab"
+Output:
+[
+  ["a","a","b"],
+  ["aa","b"],
+]
+```
+
+## How to Run in main.rs
+
+Put the code below in main.rs and run `cargo run`
+
+```rust
+  let s = String::from("aab");
+  let result = leetcode::medium::palindrome_partitioning::partition(s);
+  println!("result: {:?}", result);
+```
+
 # 138. Copy List with Random Pointer
 
 ## Description

src/readme.md

@@ -64,6 +64,7 @@
   - [x] [102. Binary tree level order traversal](../src/medium/binary_tree_level_order_traversal.rs) -> [Problem Description](../src/medium/readme.md#102-binary-tree-level-order-traversal)
   - [x] [105. Construct binary tree from preorder and inorder traversal](../src/medium/construct_binary_tree_from_preorder_and_inorder_traversal.rs) -> [Problem Description](../src/medium/readme.md#105-construct-binary-tree-from-preorder-and-inorder-traversal)
   - [x] [128. Longest consecutive sequence](../src/medium/longest_consecutive_sequence.rs) -> [Problem Description](../src/medium/readme.md#128-longest-consecutive-sequence)
+  - [x] [131. Palindrome partitioning](../src/medium/palindrome_partitioning.rs) -> [Problem Description](../src/medium/readme.md#131-palindrome-partitioning)
   - [-] [138. Copy list with random pointer](../src/medium/copy_list_with_random_pointer.rs) -> [Problem Description](../src/medium/readme.md#138-copy-list-with-random-pointer)
   - [x] [143. Reorder list](../src/medium/reorder_list.rs) -> [Problem Description](../src/medium/readme.md#143-reorder-list)
   - [x] [146. LRU cache](../src/medium/lru_cache.rs) -> [Problem Description](../src/medium/readme.md#146-lru-cache)