Add documentation about generics

[shaydewael]

Description

Specifically with regards to the action() method, if generics aren't used you'll receive TypeScript errors. This relates to #251 and #252. We should document the use of generics, possibly in a TypeScript-specific guide.

What type of issue is this? (place an x in one of the [ ])

• [ ] bug
• [ ] enhancement (feature request)
• [ ] question
• [x] documentation related
• [ ] testing related
• [ ] discussion

Requirements (place an x in each of the [ ])

• [x] I've read and understood the Contributing guidelines and have done my best effort to follow them.
• [x] I've read and agree to the Code of Conduct.
• [x] I've searched for any related issues and avoided creating a duplicate issue.

[github-actions[bot]]

👋 It looks like this issue has been open for 30 days with no activity. We'll mark this as stale for now, and wait 10 days for an update or for further comment before closing this issue out.