Describe tags used on PRs

CONTRIBUTING.md

@@ -58,7 +58,7 @@ We try to have at least two people review every pull request and we encourage ev
 - Was the change verified with several different devices and Android versions?
 - Is the code easy to understand and to maintain?
 
-Pull requests that need more [black-box testing](https://en.wikipedia.org/wiki/Black-box_testing) are tagged with `needs testing`. Pull requests that need more complete reviews including black-box testing but also review of approach and/or appropriateness are tagged with `reviews wanted`. Any contributor is encouraged to participate in both kinds of reviews!
+When a pull request is first created, @opendatakit-bot tags it as `needs review` to indicate that code review is needed. Community members review the code and leave their comments, verifying that the changes included are relevant and properly address the issue. A maintainer does a thorough code review and when satisfied with the code, tags the pull request as `needs testing` to indicate the need for a manual [black-box testing](https://en.wikipedia.org/wiki/Black-box_testing) pass. Once the behavior has been thoroughly verified, the pull request is tagged as `behavior verified`. A maintainer does a last verification and merges the changes. Pull requests that need more complete reviews including black-box testing but also review of approach and/or appropriateness are tagged with `reviews wanted`. Any contributor is encouraged to participate in the review process!
 
 Small fixes that target very particular bugs may occasionally be merged without a second review.