2011-11-24: fix readme: sitename was a tag == invisible.

fix readme: sitename was a tag == invisible.

diff --git a/README.txt b/README.txt
--- a/README.txt
+++ b/README.txt
@@ -20,7 +20,7 @@ Install:
 
 Usage:
 
-$ hg site -n <sitename> -u user:password@ftp.host.tld/path/to/dir
+$ hg site [-n sitename] -u user:password@ftp.host.tld/path/to/dir
 → that’s how this site gets created.
 
 $ hg site --help