Improve documentation

The Cosmo API documentation page is pretty good now
https://justine.lol/cosmopolitan/documentation.html

libc/calls/dup-nt.c

@@ -43,8 +43,8 @@ textwindows int dup$nt(int oldfd, int newfd, int flags) {
     return -1;
   }
   if (DuplicateHandle(GetCurrentProcess(), g_fds.p[oldfd].handle,
-                      GetCurrentProcess(), &g_fds.p[newfd].handle, 0,
-                      flags & O_CLOEXEC, kNtDuplicateSameAccess)) {
+                      GetCurrentProcess(), &g_fds.p[newfd].handle, 0, true,
+                      kNtDuplicateSameAccess)) {
     g_fds.p[newfd].kind = g_fds.p[oldfd].kind;
     g_fds.p[newfd].flags = flags;
     return newfd;