update the contributing guide to point to the script in the monorepo

CONTRIBUTING.md

@@ -1,35 +1,8 @@
 # Contributing
 
-This repository as moved into the `dbt-labs/dbt-adapters` monorepo found
+This repository has moved into the `dbt-labs/dbt-adapters` monorepo found
 [here](https://www.github.com/dbt-labs/dbt-adapters).
 Please refer to that repo for a guide on how to contribute to `dbt-athena`.
 
-If you have already opened a pull request and need to migrate it to the new repo,
-you will need to follow these steps:
-
-1. Fork `dbt-labs/dbt-adapters` and pull it down locally
-2. Migrate your feature branch from your fork of `dbt-labs/dbt-athena` to your fork of `dbt-labs/dbt-adapters`
-3. Create a new pull request in `dbt-labs/dbt-adapters` based on your feature branch
-
-Steps 1 and 3 are manual.
-Steps 2 can be accomplished by running this in your local fork of `dbt-labs/dbt-adapters`:
-
-```shell
-_USER="<your-user>"
-_BRANCH="<your-feature-branch>"
-
-# create a remote for your fork of dbt-athena
-git remote add athena-fork https://github.com/$_USER/dbt-athena.git
-git fetch athena-fork
-
-# update your feature branch
-git rebase main athena-fork/$_BRANCH
-
-# merge your feature branch from the dbt-athena repo into the dbt-adapters repo
-git checkout -b dbt-athena/$_BRANCH  # prefixing dbt-athena/ namespaces your feature branch in the new repo
-git merge athena-fork/$_BRANCH
-git push origin dbt-athena/$_BRANCH
-
-# remove the remote that was created by this process
-git remote remove athena-fork
-```
+If you have already opened a pull request and need to migrate it to the new repo, please refer to the
+[contributing guide](https://github.com/dbt-labs/dbt-adapters/blob/main/CONTRIBUTING.md#submitting-a-pull-request).