docs: Add file brief descriptions for various headers

Author: weilycoder

weilycoder/ds/group.hpp

@@ -1,6 +1,11 @@
 #ifndef WEILYCODER_GROUP_HPP
 #define WEILYCODER_GROUP_HPP
 
+/**
+ * @file group.hpp
+ * @brief Group Definitions
+ */
+
 namespace weilycoder {
 /**
  * @brief Additive Group

weilycoder/ds/point_add_range_sum.hpp

@@ -1,6 +1,11 @@
 #ifndef WEILYCODER_POINT_ADD_RANGE_SUM_HPP
 #define WEILYCODER_POINT_ADD_RANGE_SUM_HPP
 
+/**
+ * @file point_add_range_sum.hpp
+ * @brief Point Add Range Sum using Fenwick Tree
+ */
+
 #include "group.hpp"
 #include <cstddef>
 #include <stdexcept>

weilycoder/ds/static_range_sum.hpp

@@ -1,6 +1,11 @@
 #ifndef WEILYCODER_STATIC_RANGE_SUM_HPP
 #define WEILYCODER_STATIC_RANGE_SUM_HPP
 
+/**
+ * @file static_range_sum.hpp
+ * @brief Static Range Sum using Prefix Sums
+ */
+
 #include "group.hpp"
 #include <cstddef>
 #include <stdexcept>

weilycoder/ds/unionfind.hpp

@@ -1,6 +1,11 @@
 #ifndef WEILYCODER_UNIONFIND_HPP
 #define WEILYCODER_UNIONFIND_HPP
 
+/**
+ * @file unionfind.hpp
+ * @brief Union-Find (Disjoint Set Union) Data Structure
+ */
+
 #include <algorithm>
 #include <numeric>
 #include <vector>