doco lambda rest arg

[Kevin Ryde]

        * scheme-procedures.texi (Lambda): Note ". rest" list argument is
        always newly created.

After the table:

     The list in VARIABLE or VARIABLEN+1 is always newly created and
     the procedure can modify it if desired.  This is the case even
     when the procedure is invoked via `apply', the required part of
     the list argument there will be copied (*note Procedures for On
     the Fly Evaluation: Fly Evaluation.).