[pcap-ng-format] Need to figure out what to do with Experimental Blocks

[Hadriel Kaplan]

If we're going to publish this doc - either through the IETF, or even
independently create a "version 1.0" - the Experimental Blocks have to
go. Their formats and semantics are incomplete, they don't have
reserved codes, etc. They just take up space, and add confusion.

For each Experimental Block, we need to decide to either:

1. Complete it and make it no longer experimental, or...
2. Remove it from the file and add it to this github repo's wiki pages
in a "Future Work" section or some such.

-hadriel