docs: Update getting started tutorial to 3.0

[Jayclifford345]

Is your feature request related to a problem? Please describe.
As part of the docs sprint we would like to update the getting started tutorial to the latest version of Loki

[StudioLE]

For a new user the getting started experience is incredibly confusing.

Usually the README.md would include a basic docker-compose.yml that I could copy and provide me with a basic working setup.

In reality the Getting started tutorial references: https://raw.githubusercontent.com/grafana/loki/main/examples/getting-started/docker-compose.yaml which is an incredibly convoluted setup, inexplicably using yaml overrides and anchors which is of no practical use to the average user unless they want to delve deep into the complexity of yaml syntax.

So I skip that that and jump to install using docker

That tutorial points to https://github.com/grafana/loki/blob/v2.9.2/production/docker-compose.yaml which at first seems better but is a few versions old. After testing it for a bit I start to wonder where on earth the data is actually being stored and persisted.

That brings me to https://grafana.com/docs/loki/latest/configure/storage/ which shows TSDB is the recommended store. Ok, I'm already using that for prometheus so at least it's familiar. But then why isn't it a docker volume? And then it dawns that actually /etc/loki/local-config.yaml is referencing boltdb-shipper despite that being marked as deprecated and tsdb being available since 2.8?

Anyway.. This is a rambling way of a new user confirming that updating the docs is a valuable priority.

[Jayclifford345]

Hi @StudioLE, completely hear you. I am currently pushing to upgrade this to 3.0 but will focus on trying to tackle some of these concerns. We are considering a Loki fundamentals page as well which could help out a bit more with this aswell.