Improve documentation

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

libc/calls/creat.c

@@ -23,12 +23,16 @@
 /**
  * Creates new file, returning open()'d file descriptor.
  *
+ * This function is shorthand for:
+ *
+ *     open(file, O_CREAT | O_WRONLY | O_TRUNC, mode)
+ *
  * @param file is a UTF-8 string, which is truncated if it exists
  * @param mode is an octal user/group/other permission, e.g. 0755
  * @return a number registered with the system to track the open file,
  *     which must be stored using a 64-bit type in order to support both
  *     System V and Windows, and must be closed later on using close()
- * @see touch()
+ * @see open(), touch()
  * @asyncsignalsafe
  */
 nodiscard int creat(const char *file, uint32_t mode) {