I'm not aware of any KB article addressing this.

What specifically do they need/want this information for? Make sure this isn't an XY Problem before spending a bunch of time and effort putting together info that isn't ultimately useful.

That said, Laserfiche applications fall into three (or five) basic categories here:

1. Windows Service only - service does all the things the component does 
   1. Ex: Laserfiche Server, Laserfiche Full-Text Search Engine, Import Agent
2. Windows Service(s) + IIS application(s)
   1. Frontend variant - service does some of the things the component does, IIS application does the rest, communicates with the service, and includes a web presentation layer
      1. Ex: Forms (Windows Services: Forms Routing Service and Notification Hub & Master Services; IIS apps: /Forms and /FormsConfig), Directory Server (Windows Services: Directory Server; IIS apps: /LFDS and /LFDSSTS)
   2. Backend variant - service does some of the things the component does, IIS application does the rest (no real presentation layer)
      1. Ex: Workflow (Windows Services: Workflow, Workflow Subscriber; IIS app: /Workflow (web service API endpoint))
3. IIS application only - IIS app does all the things the component does
   1. Ex: Web Client (/Laserfiche), API Server (/LFWebAPI)

You'll probably find it easier to categorize each Laserfiche application component this customer uses in their system as one of the above, then link to the product documentation for the component as a whole. Going to the level of individual Windows Services does not strike me as useful in most scenarios. 

If they're asking for the purpose of configuring least-privilege network firewall rules, the best public resources I know of are here: 

https://answers.laserfiche.com/questions/154163/Default-Laserfiche-Ports-Diagram#210855