Firebase and Promises

Refs #716

Documentation/FAQ.md

@@ -174,6 +174,30 @@ func foo() -> Promise<Any>
 Who chooses when this promise starts? The answer is: Alamofire does and in this
 case, it “starts” immediately when `foo()` is called.
 
+## What is a good way to use Firebase with PromiseKit
+
+There is no good way to use Firebase with PromiseKit. See the next question for rationale.
+
+The best option is to embed your chain in your firebase handler:
+
+```
+foo.observe(.value) { snapshot in
+    firstly {
+        bar(with: snapshot)
+    }.then {
+        baz()
+    }.then {
+        baffle()
+    }.catch {
+        //…
+    }
+}
+```
+
+## I need my `then` to fire multiple times
+
+Then we’re afraid thgat you cannot use PromiseKit for that event. Promises only resolve `once`, this is the fundamental nature of promises and is considered a feature since it gives you guarantees about the flow of your chains.
+
 ## My question was not answered
 
 [Please open a ticket](https://github.com/mxcl/PromiseKit/issues/new).