docs(ion-content): directive gets its own scope

[xaka]

No description provided.

[xaka]

I'm not quite sure that ion-content should have its own scope, but as it is the case right now, people should be warned and aware of that, otherwise they'll debug their code forever :) I'd probably add a documentation section somewhere that would list all directives that get their own scopes.

[ajoslin]

I thought about removing ion-content's child scope before, but for some reason or other did not.

I don't remember why now. I think now it's too late, it would be a breaking change to make ion-content share scope with the parent.

I pushed a fix that notes this, thanks @xaka!

[fredgalvao]

Now I understand where the ghost bug I had to deal with last week came from!
Thanks for fixing it on the docs though.