Update v0.2.0 spec changes

[frenchi]

This PR primarily addresses https://github.com/openvex/examples/issues/2 - the changes introduced with v0.2.0 spec.

Also it wasn't clear why the code examples were compressed in hello-vex.zip, so this PR:

• unzips the example go files and to include them directly in the repo, and
• fixes a couple of typos.

[frenchi]

nits fixed, should be good for another review, sorry for the back and forth @puerco, this was meant to be an easy merge 😅