docs(docs): add Approach and Explanation sections with mermaid diagrams to problem pages

apps/docs/content/(array)/704-binary-search.mdx

@@ -29,6 +29,22 @@ You must write an algorithm with O(log n) runtime complexity.
 - All the integers in `nums` are unique.
 - `nums` is sorted in ascending order.
 
+## Approach
+
+```mermaid
+flowchart TD
+  S(["search(nums, target)"]) --> I["left = 0, right = n - 1"]
+  I --> W{"left <= right?"}
+  W -- no --> E(["return -1"])
+  W -- yes --> M["mid = left + floor((right - left) / 2)"]
+  M --> Q{"nums[mid] vs target"}
+  Q -- equal --> R(["return mid"])
+  Q -- "nums[mid] < target" --> L["left = mid + 1"]
+  L --> W
+  Q -- "nums[mid] > target" --> H["right = mid - 1"]
+  H --> W
+```
+
 ## Solution
 
 ```js
@@ -54,3 +70,7 @@ var search = function(nums, target) {
     return -1;
 };
 ```
+
+## Explanation
+
+<YouTube id="s4DPM8ct1pI" title="Binary Search - Leetcode 704 - Python" />