readtable: add documentation for PUSH->READ

read.scm

@@ -33,6 +33,12 @@
     (lambda ()
       (read-char port))))
 
+;;; READ:
+;;; 
+;;; (POS): Return (LIST FILENAME LINE-NUMBER OFFSET).
+;;; (READ): Read the next character in the stream. Returns #F on EOF.
+;;; (PUSH CHAR): Push CHAR such that it will be the next character read
+;;; when (READ) is called.
 (define port->read
   (lambda (read-function filename)
     (let ((line-number 1)