Documentation Error: heuristic not heuristicFunction

[wlfio]

A mistake in readme documentation

The documentation says that the heuristic function can be set with the heuristicFunction option in the constructor object, it is just heuristic

I thought of making a PR, but I feel dirty having a PR in a bigger project for just a "typo"

Edit: I have made a PR for a Cost feature for nodes, that also fixes this.

[digitsensitive]

Thanks for spotting and the PR. Since I currently not have the time to go through your PR I fixed this small problem in the documentation 👍🏼