add the --output-prefix option
diff --git a/doc/documentation.html b/doc/documentation.html
index b23d76f..d405831 100644
--- a/doc/documentation.html
+++ b/doc/documentation.html
@@ -305,7 +305,15 @@
<TT>-o filename</TT>
</TD>
<TD>
- Force the output file name (usually <TT><B>flac</B></TT> just changes the extension).
+ Force the output file name (usually <TT><B>flac</B></TT> just changes the extension). May only be used when encoding a single file. May not be used in conjunction with <TT>--output-prefix</T>.
+ </TD>
+ </TR>
+ <TR>
+ <TD NOWRAP ALIGN="RIGHT" VALIGN="TOP" BGCOLOR="#F4F4CC">
+ <TT>--output-prefix string</TT>
+ </TD>
+ <TD>
+ Prefix each output file name with the given string. This can be useful for encoding/decoding files to a different directory. Make sure if your string is a path name that it ends with a trailing '<TT>/</TT>' slash.
</TD>
</TR>
<TR>