Add doc

Author: kullingk

include/cppcore/Container/TAlgorithm.h

@@ -1,9 +1,36 @@
+/*-----------------------------------------------------------------------------------------------
+The MIT License (MIT)
+
+Copyright (c) 2014-2025 Kim Kulling
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+-----------------------------------------------------------------------------------------------*/
 #pragma once
 
 #include <cassert>
 
 namespace cppcore {
 
+/// @brief Function to calulate the distance between two iterators.
+/// @tparam TIt The container iterator
+/// @param begin    The first container iterator 
+/// @param end      The second container iterator
+/// @return The distance between the two iterators.
 template<class TIt>
 inline size_t distance(TIt begin, TIt end) {
     assert(begin < end);