Document changed default to passive mode.
diff --git a/Doc/lib/libftplib.tex b/Doc/lib/libftplib.tex
index 5e83f27..bb52f25 100644
--- a/Doc/lib/libftplib.tex
+++ b/Doc/lib/libftplib.tex
@@ -169,7 +169,8 @@
\begin{methoddesc}{set_pasv}{boolean}
Enable ``passive'' mode if \var{boolean} is true, other disable
-passive mode.
+passive mode. (In Python 2.0 and before, passive mode was off by
+default; in Python 2.1 and later, it is on by default.)
\end{methoddesc}
\begin{methoddesc}{storbinary}{command, file, blocksize}