Rename --no-mirror to --no-playback

This option impacts video and audio _playback_. For example, if we use
V4L2, the device is still "mirrored" (via V4L2), even if playback is
disabled. Therefore, "playback" is more approriate than "mirror".

The initial option --no-display option was renamed to --no-mirror by
commit 6928acdeac, but this has never been
released, so it is ok to rename it one more time.

Refs #3978 <https://github.com/Genymobile/scrcpy/pull/3978#issuecomment-1549420103>
PR #4033 <https://github.com/Genymobile/scrcpy/pull/4033>

doc/recording.md

@@ -21,10 +21,10 @@ scrcpy --no-video --audio-codec=aac --record-file=file.aac
 # .m4a/.mp4 and .mka/.mkv are also supported for both opus and aac
 ```
 
-To disable mirroring while recording:
+To disable playback while recording:
 
 ```bash
-scrcpy --no-mirror --record=file.mp4
+scrcpy --no-playback --record=file.mp4
 scrcpy -Nr file.mkv
 # interrupt recording with Ctrl+C
 ```

doc/v4l2.md

@@ -35,7 +35,7 @@ To start `scrcpy` using a v4l2 sink:
 
 ```bash
 scrcpy --v4l2-sink=/dev/videoN
-scrcpy --v4l2-sink=/dev/videoN --no-mirror  # disable mirroring window
+scrcpy --v4l2-sink=/dev/videoN --no-playback  # disable playback window
 ```
 
 (replace `N` with the device ID, check with `ls /dev/video*`)

doc/video.md

@@ -159,15 +159,15 @@ scrcpy --display-buffer=50 --v4l2-buffer=300
 ```
 
 
-## No mirror
+## No playback
 
-It is possible to capture an Android device without displaying a mirroring
+It is possible to capture an Android device without displaying a playback
 window. This option is available if either [recording](recording.md) or
 [v4l2](#video4linux) is enabled:
 
 ```bash
-scrcpy --v4l2-sink=/dev/video2 --no-mirror
-scrcpy --record=file.mkv --no-mirror
+scrcpy --v4l2-sink=/dev/video2 --no-playback
+scrcpy --record=file.mkv --no-playback
 ```