v-2021-02-04

Update instructions

Assuming your checked out version of musicbrainz-docker is v-2020-08-24 or later, then just run:

git fetch --tags origin && \
git checkout v-2021-02-04 && \
sudo docker-compose up --build -d

Only change

• Upgrade MusicBrainz Server to v-2021-02-03.1-hotfixes
  It addresses a build error related to Yarn debian public key.