Beta release vibe.d 0.7.29-beta.2

[Jacob Carlborg via Digitalmars-d-announce]

On 2016-06-02 10:27, Sönke Ludwig wrote:
> The release candidate is planned for the 6th, so please take a moment to
> test this release. Instead of `dub upgrade --prerelease`, edit
> dub.selections.json directly and put 0.7.29-beta.2 as the vibe-d version
> (there is already an alpha version of 0.7.30 out, so the upgrade would
> pick that instead).

Could you please, at one point, write documentation, or somehow 
otherwise describe the purpose of dub.selections.json?

-- 
/Jacob Carlborg