Added docblocks

[martinsik]

I went through some classes and tried to add docblocks where missing. I checked the correct syntax for @param and it always has to have proper type specified. I've also seen @override which doesn't seem to be supported by phpdoc (isn't this from Java?).

This mostly applies to 2.x branch as well.

[coveralls]

Coverage remained the same at 95.838% when pulling bf71b59 on martinsik:added-docblocks into 2429fb7 on ReactiveX:master.

[davidwdan]

@martinsik I actually removed a lot of the doc blocks in 2.x because I think that they're unnecessary where we have clear typing. I'm also not a big fan of @inheritdoc.

[davidwdan]

If anything, I would like to update the doc blocks on the operators in Observable to include more info for things like callables.

For example in the create doc block:

* @param callable(ObserverInterface $observer): DisposableInterface $subscribeAction

[martinsik]

Ok, do you want to also remove @var doc blocks? I think @var and @param are actually useful.
The updated syntax for callable is still just a proposal I think phpDocumentor/fig-standards#19 (or is it already supported by IDEs?).

[davidwdan]

@var doc blocks are okay. Just make a judgement call on where it's not clear from the types in the constructor.

I'm not sure if IDE support it or not, but it does make sense from a documentation perspective. The async interop is also using that notation: https://github.com/async-interop/event-loop/blob/master/src/Loop.php#L142 .

[martinsik]

So lets close this PR and I'll eventually open a new one.