Made contribution idea clearer in feature_request.md

[craigloewen-msft]

Summary of the Pull Request

Change 'feature request' template to also include 'contribution idea' to include the use case of people wanting to suggest fixes or improvements.

This will help with issues like these: https://github.com/microsoft/WSL/issues/12923 to make it clear you can use that template for just general ideas and fixes.

@OneBlue we should check if we can disable the 'Ask for logs' bot on these kinds of issues too.

PR Checklist

• [X] Closes: N/A
• [X] Communication: Yes
• [X] Tests: N/A
• [X] Localization: N/A
• [X] Dev docs: N/A
• [X] Documentation updated: N/A

Detailed Description of the Pull Request / Additional comments

Simple change to feature_request.md

Validation Steps Performed

N/A