Fix sentence stating TextEdit only saves in RTF; can save in plaintext as well.

Closes bug #1085300.  Thanks unclewalrus.

Doc/mac/using.tex

@@ -62,8 +62,8 @@ editor \program{BBEdit} or \program{TextWrangler} from Bare Bones Software
 (see \url{http://www.barebones.com/products/bbedit/index.shtml}) are
 good choices.  Their freeware \program{BBEdit Lite} is officially
 discontinued but still available.  \program{AppleWorks} or any other
-word processor that can save files in ASCII is also a possibility, but
-\program{TextEdit} is not: it saves in \file{.rtf} format only.
+word processor that can save files in ASCII is also a possibility, including
+\program{TextEdit} which is included with OS X.
 
 To run your script from the Terminal window you must make sure that
 \file{/usr/local/bin} is in your shell search path before \file{/usr/bin},