Add hdoordt to resources team

[hdoordt]

I'd like to get started with touching up the discovery book, as well as other learning resources that are maintained by the resources team.

Pending approval from (IIUC):

• [x] [@adamgreig]
• [x] [@eldruin]
• [ ] [@hargoniX]
• [x] [@jamesmunns]
• [ ] [@therealprof]

[adamgreig]

welcome to the team!