Use github webhooks to start build.p6

[AlexDaniel]

Currently there's simply a cron job that keeps pulling from github every few minutes. This is wasteful, and while most will not notice a delay, I've just noticed a problem with releasable.

Right after committing changes to the changelog I asked releasable what's the current status, and it replied with outdated information… Which means that you have to wait until the cron job kicks in, and then also wait for it to build rakudo on this changelog commit. D'oh.

[AlexDaniel]

This is actually relatively easy. Just set up a server and kick of the bin/build.p6 script when you receive something.

Squashable already has something like this:
https://github.com/perl6/whateverable/blob/45e09f48270c383b94d2ccf7902bed3e1787afef/bin/Squashable.p6#L136-L137
https://github.com/perl6/whateverable/blob/45e09f48270c383b94d2ccf7902bed3e1787afef/bin/Squashable.p6#L286-L301

[AlexDaniel]

This is not exactly a good first issue, but I can guide anyone to easily implement it.

[AlexDaniel]

Oh! Actually, this is already done in Buildable.