doc(wayland) Update documentation

Remove the step that tells to edit the CMakeLists.txt file
and manually enable the option to select the backend

Author: etag4048

README.md

@@ -56,7 +56,6 @@ To use wayland, adjust `lv_conf.h` as follows:
 #define LV_USE_WAYLAND		1
 ```
 
-When using SDL2, wayland or libdrm the relevant option needs to be enabled in `CMakeLists.txt`
 
 ### cmake