Documentation should add note about possible clipping for non-sinusoidal input at 0dB FS

[ed-xmos]

https://github.com/xmosnotes/an02003 already has a note about this and a pre/post gain stage for practical use.

https://github.com/xmosnotes/an02003/blob/d33241b0679add1746816b64763c03ede434670d/doc/rst/an02003.rst?plain=1#L327

See code:

https://github.com/xmosnotes/an02003/blob/d33241b0679add1746816b64763c03ede434670d/app_an02003/src/i2s_in_wrapper.xc#L62
https://github.com/xmosnotes/an02003/blob/d33241b0679add1746816b64763c03ede434670d/app_an02003/src/main.xc#L165
etc.

Some background:
https://www.xcore.com/viewtopic.php?t=8891&start=10