Fix the retrieving CPU usage information on Linux. (#4)

Author: AnatolyKalin

README.md

@@ -9,8 +9,32 @@ Status:
 * [ ] AIX
 * [ ] ...
 
-Example:
+### Example:
 
+CMakeLists.txt:
+```cmake
+cmake_minimum_required(VERSION 3.25)
+
+project(Test LANGUAGES CXX)
+
+set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_C_STANDARD 11)
+set(CXX_EXTENSIONS OFF)
+set(C_EXTENSIONS OFF)
+
+include(FetchContent)
+FetchContent_Declare(Process GIT_REPOSITORY "https://github.com/ttldtor/Process.git" GIT_TAG default)
+FetchContent_MakeAvailable(Process)
+
+add_executable(${PROJECT_NAME}
+        main.cpp
+)
+
+target_link_libraries(${PROJECT_NAME} PRIVATE process::process)
+
+```
+
+main.cpp
 ```cpp
 #include <process/process.hpp>
 

src/process.cpp

@@ -157,10 +157,10 @@ struct RUsageResult {
     std::chrono::milliseconds totalTime{};
 
     explicit RUsageResult(const rusage &ru)
-        : sysTime{static_cast<std::uint64_t>(ru.ru_stime.tv_sec) * 1000000ULL +
-                  static_cast<std::uint64_t>(ru.ru_stime.tv_usec)},
-          userTime{static_cast<std::uint64_t>(ru.ru_utime.tv_sec) * 1000000ULL +
-                   static_cast<std::uint64_t>(ru.ru_utime.tv_usec)},
+        : sysTime{static_cast<std::uint64_t>(ru.ru_stime.tv_sec) * 1000ULL +
+                  static_cast<std::uint64_t>(ru.ru_stime.tv_usec) / 1000ULL},
+          userTime{static_cast<std::uint64_t>(ru.ru_utime.tv_sec) * 1000ULL +
+                   static_cast<std::uint64_t>(ru.ru_utime.tv_usec) / 1000ULL},
           totalTime{sysTime + userTime} {
     }
 };