corrected URL for Testing Docs Page on Contributing.md

[Hailo7ts]

Description

Fixed issue #653. Changed URL to link to the Testing Docs Page inside the Contributing.md

Closes #653

Type of change

Please select everything applicable. Please, do not delete any lines.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [] This change requires a documentation update
• This change requires an update to testing

Issue

• Is this related to a specific issue? If so, please specify:
  issue Correct the URL for Testing Docs Page on 04-Contributing.md #653

Checklist:

• This PR is up to date with the main branch, and merge conflicts have been resolved
• I have executed npm run test and npm run test:e2e and all tests have passed successfully or I have included details within my PR on the failure.
• I have executed npm run lint and resolved any outstanding errors. Most issues can be solved by executing npm run format
• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings

[moses-codes]

Works as expected. Thank you for fixing this!