added a example of chaning pitch in prompt.

README.md

@@ -63,12 +63,13 @@ You must first check the available voices with the `--list-voices` option:
 
 Support for custom SSML has been removed since 5.0.0 because Microsoft has taken the initiative to prevent it from working. You cannot use custom SSML anymore.
 
-### Changing rate and volume
+### Changing rate, volume and pitch
 
 It is possible to make minor changes to the generated speech.
 
  $ edge-tts --rate=-50% --text "Hello, world!" --write-media hello_with_rate_halved.mp3 --write-subtitles hello_with_rate_halved.vtt
  $ edge-tts --volume=-50% --text "Hello, world!" --write-media hello_with_volume_halved.mp3 --write-subtitles hello_with_volume_halved.vtt
+ $ edge-tts --pitch=-50Hz --text "Hello, world!" --write-media hello_with_pitch_halved.mp3 --write-subtitles hello_with_pitch_halved.vtt
 
 In addition, it is required to use `--rate=-50%` instead of `--rate -50%` (note the lack of an equal sign) otherwise the `-50%` would be interpreted as just another argument.