improve installation step clarity, point to testing instruxions after install is complete

docs/installation_instructions.md

@@ -51,7 +51,7 @@ guide][https://openappstack.net/contact.html).
     by running `pip3 install --user venv` or `apt install python3-venv`
   * `ssh-agent` to give you access to your VPS
 
-## Install OpenAppStack CLI on your provisioning machine
+## Getting the installation script
 
 On your **provisioning machine**, clone the OpenAppStack git repository and
 checkout the latest tagged version (currently `0.3.0`):
@@ -91,9 +91,9 @@ it out by running
 
     $ python -m openappstack my-cluster --help
 
-## Install OpenAppStack on your VPS
+## Install OpenAppStack
 
-Setting up OpenAppStack on your VPS happens in three steps:
+Setting up OpenAppStack happens in three steps:
 
 1. **Set up cluster**
 
@@ -101,16 +101,15 @@ Setting up OpenAppStack on your VPS happens in three steps:
 
 2. **Install OpenAppStack**
 
-   This installs Kubernetes and all the other software that comes with
-   OpenAppStack. See [Usage](#usage) for more information on which applications
-   are installed.
+   Install Kubernetes and all the other software that comes with OpenAppStack.
+   See [Usage](#usage) for more information on which applications are installed.
 
 3. **Validate setup**
 
    This runs a test in the browser to validate that the installation was
    successful.
 
-### Set up cluster
+### Step 1: Set up cluster
 
 To set up your cluster, use the `create` subcommand of the OpenAppStack CLI.
 First, choose a name (we chose `my-cluster`) for your cluster. Then run the following command to get
@@ -123,7 +122,7 @@ API](#option-1--setup-with-the-greenhost-api) or [using any other
 machine](#option-2--setup-any-vps-or-bare-metal-server). Choose one of these
 options, and skip to the "[Installation](#installation)" subchapter afterwards.
 
-#### OPTION 1: Setup with the Greenhost API
+#### Option A: Setup with the Greenhost API
 
 - Before you can start, you need to have an API key with Customer rights.
   1. In the Cosmos service centre, click your webmaster account name on the top
@@ -191,7 +190,7 @@ options, and skip to the "[Installation](#installation)" subchapter afterwards.
   - An `A` record `oas.example.org` pointing to the VPSs IP address
   - A `CNAME` record `*.oas.example.org` pointing to `oas.example.org`.
 
-#### OPTION 2: Setup any VPS or bare metal server
+#### Option B: Setup any VPS or bare metal server
 
 Skip this step and continue to [Installation](#installation) if you already set
 up a Greenhost VPS.
@@ -245,16 +244,16 @@ testing you can skip this step. Please be aware of the limitations of this:
 - Onlyoffice won't work since it requires a valid certificate connecting to Nextcloud.
 - You need to be able to resolve the domain names locally.
 
-### Installation
+### Step 2: Installation
 
 You're almost ready to start the OpenAppStack installation script.  First, make
-sure your DNS is propagated. To do so, make sure 'ping' shows your VPS's IP
-address:
+sure your DNS configuration is propagated. To do so, make sure 'ping' shows your
+VPS's IP address:
 
     $ ping oas.example.org
 
-The `install` command will try
-to log into your machine as root using SSH.
+The `install` command will try to log into your machine as the `root`user using
+SSH.
 
 To start the installation process, run:
 
@@ -281,6 +280,12 @@ continue to the Usage section.
 > it contains the same `secrets` directory before you run the installation
 > command.
 
+### Step 3: Validate setup
+
+Because OpenAppStack is still under development, we would like you to follow our
+[testing instructions](testing_instructions) to make sure that the setup process
+went well.
+
 ## Usage
 
 After all the applications are installed, the first thing to do is log into