Refactor README

Make it easier for others to contribute with an updated README.

README.md

@@ -1,17 +1,39 @@
 # www.fossi-foundation.org website sources
 
 This repository contains the source code for the fossi-foundation.org website.
-The site is built using [Nuxt](https://nuxt.com/) and deployed to Netlify.
+The site is built using [Nuxt](https://nuxt.com/) and
+[Nuxt Content](https://content.nuxtjs.org/) and deployed to Netlify. Most
+content is written in Markdown for easier editing, with the full power of Vue
+available for advanced use cases.
 
-## Build requirements
+## Contributing content
+
+To contribute content to the website you don't need any local development setup:
+edit any Markdown file in the `content` directory and open a pull request --
+you'll get a preview build of the full website as part of the pull request.
+
+You can add new Markdown files within the existing directories in `content`
+which will show up as sub-page without further configuration.
+
+In addition to plain Markdown, you can make use of pre-defined components from
+the style guide using the
+[MDC syntax](https://content.nuxtjs.org/guide/writing/mdc). Look for existing
+pages using the `::` syntax for inspiration.
+
+## Contributing more than content
+
+To dive deeper into the website development you need a local development
+environment, either through a VS Code Dev Container, or through a native Node.js
+installation.
+
+### Option 1: Local installation
 
 Make sure that you have installed the following tools on your local machine.
 
-* Node.js 18 (LTS)
+* Node.js 18 (LTS). Other versions of Node.js might work, but also break
+  occasionally. Using a LTS version is strongly recommended.
 * Yarn
 
-## Development quickstart
-
 ```bash
 yarn install
 
@@ -27,13 +49,21 @@ yarn run build
 yarn run preview
 ```
 
-## Development quicker start
+### Option 2: VS Code Dev Container
 
 - Open with Visual Studio Code with "Dev Containers" extension installed.
 - After opening the repo, it will ask you if you want to reopen in container, which you want.
 - Run above commands or run debug target "server: nuxt"
 
-## Icons
+## Design
+
+The website design follws the the
+[FOSSi Foundation style guide](https://zeroheight.com/822235964). Make sure that
+changes to the design are also reflected in the style guide, where necessary.
+
+## Further topics
+
+### Icons
 
 We use icons from [Font Awesome Brands](https://fontawesome.com/) and
 [Phosphor Icons](https://phosphoricons.com/). To keep the bundle size low all