v-2020-10-19

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-2020-10-19 && \
sudo docker-compose up --build -d

Changes

• Allow setting the number of plackup processes for MusicBrainz Server
• Extend development setup to search (MB Solr) and indexer (SIR) services
• Upgrade MusicBrainz Server to v-2020-10-19
• Upgrade MusicBrainz Solr search server to v3.3 (including v3.2)