added info to release notes

[tiagoandresvaz]

add information to release notes and close the bug as solved. "The case-count export was restricted to the last 200 days, assuming that most people study recent dynamics. "

[vercel[bot]]

This pull request is being automatically deployed with Vercel (learn more).
To see the status of your deployment, click below or on the icon next to each commit.

🔍 Inspect: https://vercel.com/neherlab/covid19-scenarios/7ocfk9BogmnuEnvn98DWAwtVgHEL
✅ Preview: https://covid19-scenar-git-fork-tiagoandresvaz-versioninformatio-628c35.vercel.app

[rneher]

thanks!