Document the log() function

include/mtx/log.hpp

 #pragma once
 
+/// @file
+/// @brief Header for logging related functions
+
 #include <memory>
 #include <spdlog/spdlog.h>
 
 namespace mtx {
 namespace utils {
+//! Logger utilities
 namespace log {
+/// @brief Access the logger and modify it.
+///
+/// For example you can set the sinky using `mtx::utils::log::log()->sinks() = sinks` or modify the
+/// loglevel using `mtx::utils::log::log()->set_level(spdlog::level::trace)`
 std::shared_ptr<spdlog::logger>
 log();
 }