Extend the Lettuce guide on how native library conflicts are solved

[tishun]

Feature Request

Is your feature request related to a problem? Please describe

There is no documentation on what would happen if both the IO_URING and EPOLL native libraries are present in the classpath.

Describe the solution you'd like

We need to document in a clear way that:

• having both the EPOLL and IO_URING libraries in the classpath is not a valid configuration
• having them both would result in IO_URING being used
• ideally the users need to correct this by leaving only the desired library in the class path

[thachlp]

@tishun After changing the native library default to epoll, where should I update the document?

[tishun]

Hey @thachlp ,
I suggest that we put in the advanced-usage.md (Native transports section) a note, for ex.

!!! NOTE
Having both the io_uring and the epoll native transports available
in the classpath would - by default - load the io_uring driver with
precedence. Use the io.lettuce.core.iouring system property to
disable io_uring in this case and instead load the epoll transport.