Refocus installation instructions on Bazelisk

I’ve noticed that the installation guide is focused on installing Bazel directly into a system. However, it seems like Bazelisk is a preferred way of managing Bazel versions, like the Gradle wrapper is. Shouldn’t we refocus the documentation on using Bazelisk instead, omitting direct Bazel installation guides? I think it might push users into the right direction. I can be completely wrong about this however since I’m very new to the scene. I can work on it if it makes sense.