Add explicit detail about what's included in packages and tarballs when installing

The DB and CLI are separate entities but are sometimes packaged together and sometimes not.

- The tarball is just the DB. They will need to download, install, and put-in-path the CLI as well.
- The Linux packages install both by default via “recommends” (true for all Linux pkgs I’m assuming/hoping?). If users want just - - - The DB, they should run their install command with the --no-install-recommends flag (different for other non-Ubuntu/Deb?).
for Darwin, the DB comes alone as well. If the user wants the CLI, they should run brew install influxdb-cli

Start by locating the installation documentation covering tarballs, Linux packages, and Darwin. Verify which components each method installs and the commands for installing only the database or adding the CLI. Done means the package contents and CLI installation steps are explicit for each platform.

Written by the indexing model from the issue text.