[pcap-ng-format] Need to decide on the official name for this file format, and stick to it

[Hadriel Kaplan]

The document generally uses the word "pcapng" to describe the file
format, but until today used "pcap-ng" in the introduction.

It would be nice to stick to one name, at least within the document. I
just don't know what the official name is. :)

Right now it's "pcapng". Does anyone mind it staying that?

(as an aside, some web sites use "PCAP-NG" (all caps), or "PcapNg" or
other variations)

-hadriel