fix: Description is added for the extension

Fixes #47 (closed)

Short description of what this resolves:

It helps the user to know what does this extension do

Before Changes :

After Changes :

Changes proposed in this pull request:

• added this line "description": " Calculates performance-based metrics for researchers from Google Scholar profile." in the manifest.json

Checklist

• My branch is up-to-date with the Upstream develop branch.
• The acceptance, integration, unit tests and linter pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)