docs on '.dropdown-trigger' unclear

[mkropf]

Description

the docs refer to .dropdown-trigger for relative positioning, however, it does not specify where an element with that class could exist; there is no such reference in the source, are the docs out of date?

[valdrinkoshi]

fair point, the README needs to be updated... @mkropf feeling like sending a PR?
<iron-dropdown> will position itself according to the positionTarget, which defaults to its parent. The other properties for positioning are vertical/horizontalOffset and vertical/horizontalAlign.
All these properties are inherited from IronFitBehavior