docs(rust piscine): Add binary_search optional exercise subject (#2222)

* docs(rust piscine): Add binary_search optional exercise subject

* docs(rust piscine): Update binary_search subject

subjects/binary_search/README.md

@@ -0,0 +1,46 @@
+## binary_search
+
+### Instructions
+
+Write a function called `binary_search` that performs a binary search on a sorted list of integers. The function should take the following arguments:    
+- `sorted_list: &[i32]`: A reference to a sorted list of integers to search within.
+- `target: i32`: The integer value to search for within the list.
+
+### Expected Function
+
+```rust
+pub fn binary_search(sorted_list: &[i32], target: i32) -> Option<usize> {
+	// Your code goes here
+}
+```
+
+The function should return an `Option<usize>` representing the index of the `target` in the list if found, or `None` if the `target` is not in the list.
+
+### Usage
+
+Here is a possible runner to test your function:
+
+```rust
+use binary_search::binary_search;
+
+fn main() {
+    let sorted_list = vec![1, 3, 5, 7, 9, 11, 13];
+    let target = 7;
+    
+    match binary_search(&sorted_list, target) {
+        Some(index) => println!("{} found at index {}", target, index),
+        None => println!("{} not found in the list", target),
+    }
+}
+```
+
+And its output:
+
+```console
+$ cargo run
+7 found at index 3
+```
+
+### Resources
+
+- [Binary search algorithm](https://en.wikipedia.org/wiki/Binary_search_algorithm)