Fix unreadable workflow API URLs in markdown

[bibryam]

URL of the docs page
https://docs.dapr.io/developing-applications/building-blocks/workflow/howto-manage-workflow/

How is it currently worded?

How should it be worded?

Screenshots

Additional context
The http language tag makes the API commands not visible in dark red color.
Updated it to render workflow API URLs properly using code blocks for better readability.

[msfussell]

Fixed