Add an excerpt in documentation to reflect install with U#

[kay-xr]

UdonSharp contains the 0harmony.dll in its folder by default Assets/UdonSharp/Runtime/Plugins/0Harmony.dll.

While I do think this is bad practice as it is a shared library, the readme / documentation could reflect this as it will break projects when importing your harmony package on top of it.

Edit: Reported to U#, as this is more of an issue on their side. See here