Update examples to use FFI-C

[plicease]

This example:

https://github.com/Perl5-FFI/FFI-Platypus#structured-data-records

Makes more sense as a FFI-C example. Come up with a new record example that needs to pass-by-value.

Also FFI::Platypus::Record and elsewhere should have SEE ALSOs pointing to FFI-C.