The @symbols directive allows defining symbols based on image files to use inside markdown text. For example the Go servers has at its top:

  - symbol:   android
    image:    android.png
    tooltip:  Android
  - symbol:   browser
    image:    browser.png
    tooltip:  Browser
  - symbol:   ios
    image:    ios.png
    tooltip:  iOS

and these symbols are used further down by:

  Platforms indicate what clients the Go server can be accessed from