Update MentOs code to the latest development version.

programs/pwd.c

@@ -0,0 +1,17 @@
+///                MentOS, The Mentoring Operating system project
+/// @file pwd.c
+/// @brief
+/// @copyright (c) 2014-2021 This file is distributed under the MIT License.
+/// See LICENSE.md for details.
+
+#include <sys/unistd.h>
+#include <limits.h>
+#include <stdio.h>
+
+int main(int argc, char** argv)
+{
+    char cwd[PATH_MAX];
+    getcwd(cwd, PATH_MAX);
+    printf("%s\n", cwd);
+    return 0;
+}