Improve documentation

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

libc/calls/access.c

@@ -30,6 +30,7 @@
  * @param mode can be R_OK, W_OK, X_OK, F_OK
  * @return 0 if ok, or -1 and sets errno
  * @asyncsignalsafe
+ * @syscall
  */
 int access(const char *path, int mode) {
   char16_t path16[PATH_MAX];