07_tempConversion updated the readme file for clarity on the assignment

[manny53365]

Because

This provides clarity around the assignment. I updated from module.exports of spec.js file to module.exports of main javascript file.

This PR

• Provided clarity around the assignment
• Old - module.exports of spec.js file
• Updated - module.exports of main javascript file

Issue

Closes #388

Pull Request Requirements

• [x] I have thoroughly read and understand The Odin Project Contributing Guide
• [x] The title of this PR follows the location of change: brief description of change format, e.g. 01_helloWorld: Update test cases
• [x] The Because section summarizes the reason for this PR
• [x] The This PR section has a bullet point list describing the changes in this PR
• [x] If this PR addresses an open issue, it is linked in the Issue section
• [x] If this PR includes any changes that affect the solution of an exercise, I've also updated the solution in the /solutions folder