docs: Improve no-unsafe-takeuntil docs.

Closes #55.

docs/rules/no-unsafe-takeuntil.md

@@ -1,29 +1,25 @@
-# Avoid `takeUntil` subscription leaks  (`no-unsafe-takeuntil`)
+# Avoid `takeUntil` subscription leaks (`no-unsafe-takeuntil`)
 
-This rule effects failures whenever `takeUntil` is using in observable compositions that can leak subscriptions.
+This rule effects failures whenever `takeUntil` is used in observable compositions that can leak subscriptions.
+
+Although it's recommended that `takeUntil` be placed last - to ensure unsubscription from any inner observables - there are a number of operators that might _need_ to be placed after it - like `toArray` or any other operator that depends upon a `complete` notification. The rule is aware of these operators (see the rule's options, below) and will not effect failures if they are placed after `takeUntil`.
 
 ## Rule details
 
 Examples of **incorrect** code for this rule:
 
 ```ts
 const combined = source
-  .pipe(
-    takeUntil(notifier),
-    combineLatest(b)
-  )
-  .subscribe((value) => console.log(value));
+    .pipe(takeUntil(notifier), combineLatest(b))
+    .subscribe((value) => console.log(value));
 ```
 
 Examples of **correct** code for this rule:
 
 ```ts
 const combined = source
-  .pipe(
-    combineLatest(b),
-    takeUntil(notifier)
-  )
-  .subscribe((value) => console.log(value));
+    .pipe(combineLatest(b), takeUntil(notifier))
+    .subscribe((value) => console.log(value));
 ```
 
 ## Options
@@ -34,17 +30,17 @@ By default, the `allow` property contains all of the built-in operators that are
 
 ```json
 {
-  "rxjs/no-unsafe-takeuntil": [
-    "error",
-    {
-      "alias": ["untilDestroyed"]
-    }
-  ]
+    "rxjs/no-unsafe-takeuntil": [
+        "error",
+        {
+            "alias": ["untilDestroyed"]
+        }
+    ]
 }
 ```
 
 The properties in the options object are themselves optional; they do not all have to be specified.
 
 ## Further reading
 
-- [Avoiding takeUntil leaks](https://ncjamieson.com/avoiding-takeuntil-leaks/)
+-   [Avoiding takeUntil leaks](https://ncjamieson.com/avoiding-takeuntil-leaks/)