[ISSUE #744] Fix capitalization of 'DELAY' in message type attribute example

[Shuozeli]

What is the purpose of the change

Fix a typo in the delay message documentation where the message type attribute is inconsistently capitalized. This ensures consistent documentation and examples throughout the site.

Brief changelog

• Fixed capitalization of 'DELAY' in message type attribute example in the delay message documentation file (/i18n/en/docusaurus-plugin-content-docs/version-5.0/04-featureBehavior/02delaymessage.md)

Issue reference

Fixes #744

Verifying this change

The change can be verified by checking that the message type attribute is consistently shown as 'DELAY' in uppercase in all examples in the documentation.

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