Include some statistics: How many users used it at peak? Not sure if exact numbers exist, but maybe compare to Flash's usage.
Check for any common misconceptions. For example, some might confuse Shockwave with the audio format. Clarify that it's a web plugin, not a file format. shockwave plugin
In the decline section: The rise of HTML5, JavaScript, WebGL made plugins like Shockwave obsolete. Security issues were a big problem. Also, the shift to mobile where plugins didn't work. Adobe's announcement to phase out Shockwave, same as Flash, due to security and performance issues. Include some statistics: How many users used it at peak