version: include version in produced docs

[vbatts]

Fixes #398

This produces a markdown page as a header for the PDF and HTML pages.

Signed-off-by: Vincent Batts [email protected]

[wking]

On Wed, Apr 27, 2016 at 07:54:30AM -0700, Vincent Batts wrote:
“ A .tool/version-doc.go (25)”

This is depressingly large when an inline:

$ sed -n 's/."ociVersion": *"([^"])",/Specification Version: \1/p' config.md

would do the same thing (assuming we update the example 1). But
maybe relying on Go is more portable than relying on sed? On the
other hand, systems that have ‘make’ are likely to have ‘sed’.

Aside from that minor grump, 73ef76d looks good to me.

[crosbymichael]

LGTM

plz rebase