linux install instructions don't include docker-compose instructions

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Please complete the following:

Link to the page that needs to be updated or changed. https://docs.lando.dev/basics/installation.html#linux

Describe the change you'd like Requirements state that Docker CE is required, but don't note that docker compose is also required. When I followed these instructions on Ubuntu 20.10, I had to find and install Docker Compose separately. Would recommend that we add instructions for installing this as well. Particularly because Lando wants a specific version of it (I installed the latest and received an error message that it wasn't in the range lando preferred).