Be able to configure PR description suffix

[addison-grant]

In our organization, we parse text in pull descriptions and comments for keywords that are used in our review process. It would be nice if we could automatically add some keywords for dependabot PR descriptions.

For example, dependabot created this PR description:

Bumps [mixin-deep](https://github.com/jonschlinkert/mixin-deep) from 1.3.1 to 1.3.2.
<details>
<summary>Commits</summary>

- [`754f0c2`](https://github.com/jonschlinkert/mixin-deep/commit/754f0c20e1bc13ea5a21a64fbc7d6ba5f7b359b9) 1.3.2
- [`90ee1fa`](https://github.com/jonschlinkert/mixin-deep/commit/90ee1fab375fccfd9b926df718243339b4976d50) ensure keys are valid when mixing in values
- See full diff in [compare view](https://github.com/jonschlinkert/mixin-deep/compare/1.3.1...1.3.2)
</details>
<details>
<summary>Maintainer changes</summary>

This version was pushed to npm by [doowb](https://www.npmjs.com/~doowb), a new releaser for mixin-deep since your current version.
</details>
<br />

[![Dependabot compatibility score](https://dependabot-badges.githubapp.com/badges/compatibility_score?dependency-name=mixin-deep&package-manager=npm_and_yarn&previous-version=1.3.1&new-version=1.3.2)](https://help.github.com/articles/configuring-automated-security-fixes)

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<details>
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</details>

I would like to be able to customize this, or be able to suffix it with

[custom suffix string]

Maybe something like

version: 1
update_configs:
  - package_manager: "javascript"
    directory: "/"
    update_schedule: "daily"
    pr_description:
        suffix: "\nmy custom suffix string"

Hope that makes sense!

[addison-grant]

This would probably work for us, too: #2211. I wasn't sure if that or this would be easier to implement.

[rebelagentm]

Thanks for submitting this! We're pretty swamped at the moment, but we'll take this under consideration as soon as we can.

[addison-grant]

Sounds good

[boomboompower]

Any updates on this?

[TheRealWaldo]

We're also in a position where having a PR and commit message suffix would allow us to use dependabot without changing our messaging standards.

[addison-grant]

I didn't see #1446 before. @TheRealWaldo, I mentioned in a comment above https://github.com/dependabot/feedback/issues/287 as another thing that would solve this, maybe in a more general way.

[TheRealWaldo]

@addison-grant agreed, could work, but likely to be much more work (and a much longer wait) than adding a suffix field.

[lavigne958]

Hi, I'll be very interested too in a configuration entry for dependabot to post a new comment in the PR when it opens a new PR, we parse PR comments too.

In our case we don't parse the first message that opens the PR but any message that comes after.

Thank you guys in advance if you could plan that new feature 🙂