Fix #89: Add RISEN framework to README and CONTRIBUTING-

[Ayushmann13479]

Fixes #89

Added the RISEN framework (Role, Instructions, Steps, End Goal, Narrowing) to both README.md and CONTRIBUTING.md.

Changes:

• README.md: Added a "Prompt Frameworks" section with a RISEN reference table and a ServiceNow-specific example
• CONTRIBUTING.md: Added RISEN guidance under the "Think of a Prompt" section to help contributors write better-structured prompts