docs: Explain how to use AppRunner to start a server instance

documentation/markdown/usage/dev-configuration.md

@@ -1,6 +1,61 @@
 # Configuring the CSS as a development server in another project
 
 It can be useful to use the CSS as local server to develop Solid applications against.
+There are several ways to configure and run a server in your project.
+
+## Starting the server through code
+
+You can create a server instance in your code, or tests, by calling the `create` function of a new `AppRunner` instance.
+The resulting object has `start` and `stop` functions.
+The `create` function takes as input an object with 5 optional parameters
+which can all be used to define the server configuration.
+None of these are mandatory, if you don't think you need one you can probably ignore it.
+These are discussed below.
+
+### loaderProperties
+
+These values are specifically to configure how Components.js handles starting the server.
+Most of these are generally not going to be relevant,
+but here are some of those you might want to change:
+
+* **mainModulePath**: Determines where Components.js will look for components.
+                        Defaults to the folder where the server dependency is installed.
+                        In case you are making a custom component,
+                        this value needs to point to the directory of your project instead.
+* **logLevel**: The logging level of Components.js when building. Defaults to `warn`.
+
+### config
+
+The file path of the Components.js configuration that needs to be used.
+This can also be an array of configuration paths.
+The `@css:` prefix can be used for file paths to generate a path
+relative to the folder where the server dependency is installed.
+Defaults to `@css:config/default.json`.
+
+### variableBindings
+
+Allows you to assign values to the variables that are used in a Components.js configuration.
+For example, `{ 'urn:solid-server:default:variable:port': 3000  }` tells the server to use port 3000.
+
+### shorthand
+
+Allows you to assign values to parameters similarly as if you would call the server from the CLI.
+For example, `{ port: 3000  }` tells the server to use port 3000.
+
+This is very similar to the `variableBindings` field mentioned above,
+as CLI parameters all get translated into Components.js variables,
+although some get transformed before being put into a variable.
+If you are not sure which one to use, `shorthand` is the safer choice to use.
+
+### argv
+
+If used, this parameter expects a string array.
+Here you can provide the raw dump of CLI values,
+so you don't have to parse them yourself,
+should this be useful for your application.
+
+## Configuring the server in `package.json`
+
 As an alternative to using CLI arguments, or environment variables, the CSS can be configured in the `package.json` as follows:
 
 ```json
@@ -24,7 +79,7 @@ As an alternative to using CLI arguments, or environment variables, the CSS can
 ```
 
 These parameters will then be used when the `community-solid-server`
-command is executed as an npm script (as shown in the example above).
+command is executed as an `npm` script (as shown in the example above).
 Or whenever the `community-solid-server` command is executed in the same
 folder as the `package.json`.