Documentation should use polaris binary distribution first

Today, getting start assumes user checked out the repository and it's based on the repository, including build/execute with `gradlew`.
Now that we have the binary distribution, the getting start should be "easier"/"smoother", directly using the binary distribution (`bin/server`, `bin/admin`) instead of `gradlew`.
We should keep the user of `gradlew` in a "integration/deployment" section.

Start by locating the getting-started documentation and the existing instructions that use gradlew. Update the getting-started flow to use the binary distribution entry points bin/server and bin/admin, while keeping gradlew under an integration/deployment section; done when the documented quick start no longer requires checking out and building the repository.

Written by the indexing model from the issue text.