Fix ref_type description in delete webhook

[mkrystek]

Why:

Fixed oject typo and aligned rest of description with similar description of create webhook

What's being changed:

Small description of ref_type property of delete webhook payload

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[cmwilson21]

@mkrystek Thanks so much for opening a PR! I'll get this triaged for review ⚡

[cmwilson21]

These changes look great! I'll get this merged once the test are all passing ⚡

Thank you for your passion in improving our docs! ✨

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