ci: rebuild tip.cuelang.org on master commits
ci: rebuild tip.cuelang.org on master commits

When a new commit is submitted to master we need to trigger a rebuild of
tip.cuelang.org in order than the @master docs are updated as required.

Do that via a simple GitHub action.

Change-Id: I9d1b404756358f357c7906a4f38897c6337b4f32
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/5300
Reviewed-by: Marcel van Lohuizen <a22d082192f3ccf984644a4f482781f4c2d65180@golang.org>

cuelang/cue