Document the PDSET C command.

doc/sysdoc/pdset.info

@@ -40,6 +40,9 @@ D  SET DATE. ACCEPTS A SIX
    IF NOT SUPPLIED, THEN SETS A FLAG
    TO USE THE SYSTEM DATE (INITIAL MODE).
 
+C  SET CENTURY. ACCEPTS A TWO
+   DIGIT LEADING ARGUMENT.
+
 T  SELECT *THE *TIME *AT *WHICH *THE
    *SETLOC *COMMAND *WILL *BE *GIVEN*.
    (HHMMSS 24 HR-TYPE LEADING ARGUMENT).

src/sysen1/pdset.115

@@ -445,7 +445,7 @@ SBKUP:	.RDTIME A,	;SEE HOW LONG IT'S BEEN SINCE . TYPED
 	JRST DOIT2	;DO THE .SETLOC, THEN SET YEAR
 	POPJ P,		;NOT DEFINED, NOTHING ELSE TO DO
 
-	CMD "C,CENSET
+	CMD "C,CENSET,SET CENTURY (precede by NN, for example 20C)
 
 CENSET:	PUSHJ P,ARGET	;GET CENTURY (-1)
 	MOVEI A,19.	;NO ARG, RESET TO DEFAULT