doc/muxers: remove hls_fmp4_init_resend parameter

the parameter should boolean

doc/muxers.texi

@@ -847,7 +847,7 @@ fmp4 files may be used in HLS version 7 and above.
 @item hls_fmp4_init_filename @var{filename}
 Set filename to the fragment files header file, default filename is @file{init.mp4}.
 
-@item hls_fmp4_init_resend @var{filename}
+@item hls_fmp4_init_resend
 Resend init file after m3u8 file refresh every time, default is @var{0}.
 
 When @code{var_stream_map} is set with two or more variant streams, the