Add Start9 to the node page (Hardware section)

[JesseMarkowitz]

Please add Start9 to the node page (https://github.com/BitcoinDesign/Guide/blob/master/guide/how-it-works/node.md) in the Hardware section

The line that says:

Several plug-and-play hardware node options exist such as Umbrel, MyNode, RoninDojo, and Raspiblitz.

could be changed to:

Several plug-and-play hardware node options exist such as Umbrel, MyNode, RoninDojo, Start9, and Raspiblitz.

[GBKS]

This was completed via #1055.