Readme is outdated

[agoncharov-reef]

After trying to follow the manual setup instruction in README, it turned out that not all steps are working, like:

• copying post-receive file - env vars are substituted
• www domain is not needed sometimes
• github creates main branch, not master
• fe_sendauth: no password supplied (WAT?) - because postgres password should be set in TWO places in .env file
• nginx doesn't start without cadvisor (even if I don't need the latter); cadvisor doesn't start w/o monitoring certificates
• no need to install docker-compose since it's now docker compose; update scripts to use new version