Make the API easier to use and add better/more robust documentation

[joeldesante]

The API is a bit confusing to use and the documentation I have currently provided is not helping the matter. It seems that many have gotten by with what has been provided but I feel that it is too hard to do simple things that one would expect this library to do like basic particle movement.

Right now to do particle movement you need to explicitly program this behavior like seen in the following example:

local emitter = ParticleEmitter.new(script.Parent, game.ReplicatedStorage.Particle)
emitter.onSpawn = function(particle)
	particle.velocity = Vector2.new(math.random(-3,3) / 3 + 0.1, math.random(-3,3) / 3 + 0.1)
end

emitter.onUpdate = function(particle, delta)
	particle.position = particle.position + particle.velocity
end

While this makes the library very small and light weight there is essentially no "hand holding" done by the module. There have been attempts to solve this problem in forks of the module such as UI Particle but it would be nice to have some of these quality of life features in the main module.