Mention pinned yarn version - There used to be some text in the README explaining that the yarn version had to match what's in the package.json This just readds that text.
Mention pinned yarn version
- There used to be some text in the README explaining
that the yarn version had to match what's in the package.json
This just readds that text.


Former-commit-id: 383fb77825071ef8a34c95dce8e01f11fe1450b7
cBioPortal/cbioportal-frontend,cBioPortal/cbioportal-frontend,alisman/cbioportal-frontend,cBioPortal/cbioportal-frontend,alisman/cbioportal-frontend,alisman/cbioportal-frontend,alisman/cbioportal-frontend,cBioPortal/cbioportal-frontend,cBioPortal/cbioportal-frontend,cBioPortal/cbioportal-frontend,alisman/cbioportal-frontend,alisman/cbioportal-frontend