mount() oneliner in docs should be clearer

[getaaron]

The ReactWrapper docs say:

.mount() => ReactWrapper

A method that re-mounts the component.

A developer using Enzyme who reads this one-liner without reading the full docs will incorrectly believe that a call to mount() will re-mount any component. In fact, this method will only mount an unmounted component. It will do nothing if the component is already mounted.

A more precise summary would be something like:

.mount() => ReactWrapper

A method that (re-)mounts the component, if it is not currently mounted.

mount.md and the comments in ReactWrapper.js would need to be updated as well.