libc: Document sys/types.h

libs/libc/include/sys/mman.h

@@ -20,6 +20,7 @@ extern "C"
     /* Maps size bytes of memory (rounded down to the nearest page-aligned size) into the current process's address
      * space at addr. If addr is null, the kernel will choose an address. */
     void* mmap(void* addr, size_t size, int prot, int flags, int fd, off_t offset);
+
     /* Unmaps size bytes of memory (rounded down to the nearest page-aligned size) at addr from the current process's
      * address space. */
     int munmap(void* addr, size_t size);

libs/libc/include/sys/types.h

@@ -1,8 +1,13 @@
 #ifndef _SYS_TYPES_H
 #define _SYS_TYPES_H
 
+/* The type of a process identifier. */
 typedef long int pid_t;
+
+/* The type returned by sizeof(). */
 typedef unsigned long int size_t;
+
+/* Signed version of size_t. */
 typedef long int ssize_t;
 
 #endif