[ADD] add details in Coyote Readme

[KoalaYuFeng]

I add some details:

1. Before typing 'hdev examine', we need to set the environmental variables.
2. Before compiling, we should set the VIVADO version. In my experiment, I compile the kernel using 2022.2 version, it can generate the correct bit file, but when I doing 'Program FPGA + Insert Driver via hdev' typing 'hdev program xxx', it returns a message 'Please, choose a valid Vivado version.' Finally, I tried 2022.1 vivado and it works fine. So I suggest to add version details.