chore(types, utils): update the TSDocs of AbstractFulfillmentProviderService (#9349)

Updates the `AbstractFulfillmentProviderService` with TSDocs for more useful information and examples

Closes DOCS-950

packages/modules/providers/fulfillment-manual/src/services/manual-fulfillment.ts

@@ -1,4 +1,5 @@
 import { AbstractFulfillmentProviderService } from "@medusajs/framework/utils"
+import { FulfillmentOption } from "@medusajs/types"
 
 // TODO rework type and DTO's
 
@@ -9,7 +10,7 @@ export class ManualFulfillmentService extends AbstractFulfillmentProviderService
     super()
   }
 
-  async getFulfillmentOptions(): Promise<Record<string, unknown>[]> {
+  async getFulfillmentOptions(): Promise<FulfillmentOption[]> {
     return [
       {
         id: "manual-fulfillment",