Add "Getting started" section to main README

We were linking to the "guided installation" even now, but there are so
many links and no explicit "Getting started" link anywhere.
This tries to make things better.

Inspired by:

- https://news.ycombinator.com/item?id=42039447
- https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/3744

README.md

@@ -8,17 +8,24 @@ This [Ansible](https://www.ansible.com/) playbook is meant to help you run your
 
 That is, it lets you join the Matrix network using your own `@<username>:example.com` identifier, all hosted on your own server (see [prerequisites](docs/prerequisites.md)).
 
-We run all services in [Docker](https://www.docker.com/) containers (see [the container images we use](docs/container-images.md)), which lets us have a predictable and up-to-date setup, across multiple supported distros (see [prerequisites](docs/prerequisites.md)) and [architectures](docs/alternative-architectures.md) (x86/amd64 being recommended).
+We run all [supported services](#supported-services) in [Docker](https://www.docker.com/) containers (see [the container images we use](docs/container-images.md)), which lets us have a predictable and up-to-date setup, across multiple supported distros (see [prerequisites](docs/prerequisites.md)) and [architectures](docs/alternative-architectures.md) (x86/amd64 being recommended).
-
-[Installation](docs/README.md) (upgrades) and some maintenance tasks are automated using [Ansible](https://www.ansible.com/) (see [our Ansible guide](docs/ansible.md)).
 
+Installation (upgrades) and some maintenance tasks are automated using [Ansible](https://www.ansible.com/) (see [our Ansible guide](docs/ansible.md)).
 
 ## Self-hosting or Managed / SaaS
 
-This Ansible playbook tries to make self-hosting and maintaining a Matrix server fairly easy. Still, running any service smoothly requires knowledge, time and effort.
+This Ansible playbook tries to make self-hosting and maintaining a Matrix server fairly easy (see [Getting started](#getting-started)). Still, running any service smoothly requires knowledge, time and effort.
 
 If you like the [FOSS](https://en.wikipedia.org/wiki/Free_and_open-source_software) spirit of this Ansible playbook, but prefer to put the responsibility on someone else, you can also [get a managed Matrix server from etke.cc](https://etke.cc?utm_source=github&utm_medium=readme&utm_campaign=mdad) (both hosting and on-premises) - a service built on top of this Ansible playbook but with [additional components](https://etke.cc/help/extras/?utm_source=github&utm_medium=readme&utm_campaign=mdad) and [services](https://etke.cc/services/?utm_source=github&utm_medium=readme&utm_campaign=mdad) which all help you run a Matrix server with ease. Be advised that etke.cc operates on a subscription-based approach and there is no "just set up my server once and be done with it" option.
 
+## Getting started
+
+We have detailed documentation in the [docs/](./docs) directory - see the Table of Contents in the [documentation README](./docs/README.md).
+
+While the [list of supported services](#supported-services) and documentation is very extensive, you don't need to read through everything. We recommend:
+
+- Starting with the basics. You can always add/remove or tweak services later on.
+- Following our guided installation, starting with the [Prerequisites](./docs/prerequisites.md) documentation page
 
 ## Supported services