Migrate old data.okfn.org vision docs to blog post on labs (or datahub)

[rufuspollock]

vision.md -> post to okfn labs blog
vision-appendix.md -> post to okfn labs blog

Old data.okfn.org docs - https://github.com/okfn/data.okfn.org-new/tree/master/doc:

[zelima]

WONTFIX think this is obsolete now. re-open if no

[rufuspollock]

@zelima this is not obsolete. Please can we do this ...

[zelima]

@tanvirchahal / @anuveyatsu can you publish those 2 posts on datahub? Adding to the next milestone