extensions: Add author to the manifest (#10134)

Related to #9910 
Also, this PR will add a release note, since I've missed that in the
original PR.
Release Notes:

- Added Emmet language extension to the extension store.
79272b75e3Piotr Osiewicz committed on 4/3/2024, 6:18:31 PM· committed by GitHubparent0ddec27
1 file changedLine totals unavailable