Fix link in PR template

[moleske]

Thank you for submitting a pull request to the bbs repository!

We appreciate the contribution. To help us understand the context for your pull request, please fill out this template to the best of your ability.

Please make sure to complete all of the following steps

1. Check the Contributing document on how to sign the CLA and run tests.
2. Submit your PR to this repo.
3. Submit an accompanying PR Review Request referencing this PR so the Diego Team knows to review your pull request.

• Note: this PR will not be reviewed unless you submit the PR Review Request.

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Please provide the following information:

What is this change about?

Correct link to generate title of Diego Release PR

What problem it is trying to solve?

Not being confused by the generated PR title

What is the impact if the change is not made?

Will be confused next time I open a PR

How should this change be described in diego-release release notes?

It shouldn't be listed in the release notes

Please provide any contextual information.

none

Tag your pair, your PM, and/or team!

no one

Thank you!