Documentation Fix

I found a small typo in the RocketMQ documentation that I'd like to fix:

Location:
File: /i18n/en/docusaurus-plugin-content-docs/version-5.0/04-featureBehavior/02delaymessage.md
Line: 100

Issue:
Inconsistent capitalization of the message type attribute. Currently shows +message.type=Delay (lowercase "Delay") while the correct format shown in line 110 is +message.type=DELAY (uppercase "DELAY").

Proposed Fix:
Change +message.type=Delay to +message.type=DELAY to maintain consistency throughout the documentation.

Importance:
This is a minor documentation improvement to ensure consistency in code examples.