I came for something else, but one thing led to another...

Emit a proper summary at the top, but elide ENUMs to keep it
compact.

If the entire VCL prototype fits in the header, put it there.
else if it fits with ENUMs elided do that or finally resort
to just the name + "(...)".

If the header didn't hold the full prototype, emit a codeblock
with it, and split that in one line per argument if it is too
wide for the manual pages.

Remove the manual summary from the libvmod_blob docs.

otherwise summarize it (ie: elide ENUMs)