Update cURL examples in the style guide

What does this MR do?

The table under cURL commands has examples using -H and -X VERB. However, in examples below it there are expanded options --header and --request respectively. As far as I recall, we also check for abbreviated versions in the linter and pipelines.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

N/A - change in content

Security

N/A