[ih] IEN index hyperlinked

[Bob Braden]

In doing historical research in the IEN series, I got tired of
skipping between ien-index.txt and the directory of text, so I produced
a hyper-linked index ien-index.html.

It is at ftp://ftp.rfc-editor.org/in-notes/ien/ien-index.html,
or accessible from http://www.rfc-editor.org/RFCoverview.html#history.
It's a little crude, but it works.

There are still quite a few IENs missing in the .txt form.  I know that
someone has pdf scans of the missing ones, and one of these days I will
find out who that is and put them into the directory.

Bob Braden