Develompent builds are the bleeding-edge of the current development. They are released for testing after any major change. I'll be more than happy if you send me feedback on those builds and report issues.
Keep in mind development builds might not update automatically upon release of the next version. They are experimental, so they most likely contain bugs and regressions. Thus you are using these builds at your own risk.
You find the development builds on the release page side by side with the normal releases but they are tagged as prerelease. This might sound confusing but it is the github way to do this.