Update CONTRIBUTING to mention PR labels (#1554)

The repository is updated to use release-drafter,
so it'd be polite to let others know about the
labels.

CONTRIBUTING.md

@@ -2,6 +2,7 @@
 
 If you are interested in contributing to NVTabular your contributions will fall
 into three categories:
+
 1. You want to report a bug, feature request, or documentation issue
     - File an [issue](https://github.com/nvidia/NVTabular/issues/new/choose)
     describing what you encountered or what you want to see changed.
@@ -23,15 +24,18 @@ into three categories:
 ### Your first issue
 
 1. Read the project's [README.md](https://github.com/nvidia/NVTabular/blob/main/README.md)
-    to learn how to setup the development environment
-2. Find an issue to work on. The best way is to look for the [good first issue](https://github.com/nvidia/NVTabular/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22)
-    or [help wanted](https://github.com/nvidia/NVTabular/issues?q=is%3Aissue+is%3Aopen+label%3A%22help+wanted%22) labels
-3. Comment on the issue saying you are going to work on it
+    to learn how to setup the development environment.
+2. Find an issue to work on. The best way is to look for the
+   [good first issue](https://github.com/nvidia/NVTabular/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22)
+   or [help wanted](https://github.com/nvidia/NVTabular/issues?q=is%3Aissue+is%3Aopen+label%3A%22help+wanted%22) labels.
+3. Comment on the issue saying you are going to work on it.
 4. Code! Make sure to update unit tests!
-5. When done, [create your pull request](https://github.com/nvidia/NVTabular/compare)
-6. Verify that CI passes all [status checks](https://help.github.com/articles/about-status-checks/). Fix if needed
-7. Wait for other developers to review your code and update code as needed
-8. Once reviewed and approved, a developer will merge your pull request
+5. When done, [create your pull request](https://github.com/nvidia/NVTabular/compare).
+6. Verify that CI passes all [status checks](https://help.github.com/articles/about-status-checks/).
+   Fix if needed.
+7. Wait for other developers to review your code and update code as needed.
+8. After your pull request reviewed and approved, a maintainer will merge your
+   pull request.
 
 Remember, if you are unsure about anything, don't hesitate to comment on issues
 and ask for clarifications!
@@ -49,5 +53,31 @@ contributing to. Start with _Step 3_ from above, commenting on the issue to let
 others know you are working on it. If you have any questions related to the
 implementation of the issue, ask them in the issue instead of the PR.
 
+## Label your PRs
+
+This repository uses the release-drafter action to draft and create our change log.
+
+Please add one of the following labels to your PR to specify the type of contribution
+and help categorize the PR in our change log:
+
+- `breaking` -- The PR creates a breaking change to the API.
+- `bug` -- The PR fixes a problem with the code.
+- `feature` or `enhancement` -- The PR introduces a backward-compatible feature.
+- `documentation` or `examples` -- The PR is an addition or update to documentation.
+- `build`, `dependencies`, `chore`, or `ci` -- The PR is related to maintaining the
+  repository or the project.
+
+By default, an unlabeled PR is listed at the top of the change log and is not
+grouped under a heading like *Features* that groups similar PRs.
+Labeling the PRs so we can categorize them is preferred.
+
+If, for some reason, you do not believe your PR should be included in the change
+log, you can add the `skip-changelog` label.
+This label excludes the PR from the change log.
+
+For more information, see `.github/release-drafter.yml` in the repository
+or go to <https://github.com/release-drafter/release-drafter>.
+
 ## Attribution
-Portions adopted from https://github.com/pytorch/pytorch/blob/master/CONTRIBUTING.md
+
+Portions adopted from <https://github.com/pytorch/pytorch/blob/master/CONTRIBUTING.md>.