pgindent README correction

I found that I needed to adjust the command given in the README file
for pgindent. Trivial patch attached.

The one other issue I ran into in following the latest pgindent
instructions was that I had to add #include <stdlib.h> to the
parse.c file (as included in the pg_bsd_indent-1.1.tar.gz file at
ftp://ftp.postgresql.org/pub/dev ). Without it I got this:

parse.c: In function *parse*:
parse.c:236:6: warning: implicit declaration of function *exit*
parse.c:236:6: warning: incompatible implicit declaration of built-in
function *exit*

Can someone fix that and put up a 1.2 version?

-Kevin