Fix wrong indent for examples of controlnet script

[Justin900429]

What does this PR do?

Fix the wrong indentation for the example scripts.

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
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  here are tips on formatting docstrings.
• Did you write any new necessary tests?

Who can review?

@sayakpaul @yiyixuxu

[HuggingFaceDocBuilderDev]

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