doc: fix toolname

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

doc/ffmpeg.texi

@@ -823,7 +823,7 @@ ffmpeg -i INPUT -map 0 -map -0:a:1 OUTPUT
 
 To pick the English audio stream:
 @example
-avconv -i INPUT -map 0:m:language:eng OUTPUT
+ffmpeg -i INPUT -map 0:m:language:eng OUTPUT
 @end example
 
 Note that using this option disables the default mappings for this output file.

doc/fftools-common-opts.texi

@@ -51,7 +51,7 @@ Matches streams with the metadata tag @var{key} having the specified value. If
 @var{value} is not given, matches streams that contain the given tag with any
 value.
 
-Note that in @command{avconv}, matching by metadata will only work properly for
+Note that in @command{ffmpeg}, matching by metadata will only work properly for
 input files.
 @end table