Fix typo in README

Refs <https://github.com/Genymobile/scrcpy/pull/2195#discussion_r595664697>

README.md

@@ -420,7 +420,7 @@ _(left)_ and <kbd>MOD</kbd>+<kbd>→</kbd> _(right)_.
 
 Note that _scrcpy_ manages 3 different rotations:
  - <kbd>MOD</kbd>+<kbd>r</kbd> requests the device to switch between portrait
-   and landscape (the current running app may refuse, if it does support the
+   and landscape (the current running app may refuse, if it does not support the
    requested orientation).
  - [`--lock-video-orientation`](#lock-video-orientation) changes the mirroring
    orientation (the orientation of the video sent from the device to the