Configure Bulldozer to update PRs when tagged with 'Update Me'. (#3717)
Configure Bulldozer to update PRs when tagged with 'Update Me'. (#3717)

* Configure Bulldozer to update PRs when tagged with 'Update Me'.

* Add merge when ready to update section.

allenai/allennlp,allenai/allennlp,allenai/allennlp,allenai/allennlp