Add informatinon about Freelens to README.md

[petolexa]

Hello, please consider applying my change. I found it beneficial to mention a new stream in the form of Freelens project at OpenLens README, as the repository is still being visited and has a decent user base.

[dex4er]

Hi. I'm contributor of Freelens and I would like to admit that @MuhammedKalkan did an amazing work in this repository and it was a great help when I implemented the Github Actions pipelines for Freelens. Thank you!