doc: fixes wrong identation in a code block

[Brice187]

Checklist:

• Commit Message Formatting: Commit titles and messages follow guidelines in the developer guide.
• Reviewed the developer guide on Submitting a Pull Request
• Pending release notes updated with breaking and/or notable changes for the next minor release. <- Just fixed a small typo, not worth to mention
• Documentation has been updated, if necessary.
• Unit tests have been added, if necessary.
• Integration tests have been added, if necessary.

Small fix

Wrong formatting in the docs (You should not see 3 backticks and the reserved keyword YAML):

[travisn]

Please see the first point in the PR checklist:

• Commit Message Formatting: Commit titles and messages follow guidelines in the developer guide

The Commitlint and DCO CI actions are failing because the commit message needs to follow this pattern.

Thanks for submitting the fix!

[travisn]

Interesting that later in the doc there are similar instances, but they are rendered properly, perhaps because they under under bulleted points.

[mergify]

This pull request has merge conflicts that must be resolved before it can be merged. @Brice187 please rebase it. https://rook.io/docs/rook/latest/Contributing/development-flow/#updating-your-fork