doc-fix : clang and cmake skeleton generation doc update for ebpf

[abhi-jha]

Update dependencies and build command for ebpf programs

[abhi-jha]

I now also realise that a specific version of clang might be required but I have still not been able to compile it end to end.

[ 89%] Building C object plugins/in_ebpf/CMakeFiles/flb-plugin-in_ebpf.dir/in_ebpf.c.o
In file included from /home/ubuntu/GIT/temp/fluent-bit/plugins/in_ebpf/in_ebpf.c:24:
/home/ubuntu/GIT/temp/fluent-bit/plugins/in_ebpf/traces/traces.h:6:10: fatal error: generated/trace_signal.skel.h: No such file or directory
    6 | #include "generated/trace_signal.skel.h"
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
make[2]: *** [plugins/in_ebpf/CMakeFiles/flb-plugin-in_ebpf.dir/build.make:63: plugins/in_ebpf/CMakeFiles/flb-plugin-in_ebpf.dir/in_ebpf.c.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:6655: plugins/in_ebpf/CMakeFiles/flb-plugin-in_ebpf.dir/all] Error 2
make: *** [Makefile:152: all] Error 2

[abhi-jha]

Should I add a disclaimer that it only works right now on ubuntu 24.04?

[lockewritesdocs]

This PR needs a review from @fluent/fluent-bit-maintainers -- cc: @patrick-stephens