[fpc-pascal] Documentation patch for fcl/netdb

[Noel Duffy]

I've added a documentation patch to bug 0037906 in the bug tracker. This 
covers the new code that I added to fcl/netdb for DNS resolution as well 
most of the other functions and procedures in the unit. The patch also 
adds examples that showcase the new functions. I've tested these on 
Fedora 32 only.

https://bugs.freepascal.org/view.php?id=37906#c130418