Update docs

docs/tut/crash-course/6-root.md

@@ -1,7 +1,7 @@
 # Root Reactive Scopes
 
-Any reactive scopes created, such as one from `effect()`, must be done so within
-a "root" reactive scope. This is the main purpose of `mount()`, which you use
+Any reactive scopes created, such as by `effect()`, must be done so within a
+"root" reactive scope. This is the main purpose of `mount()`, which you use
 once at the top level to create your app as shown in the first introduction.
 
 This is so that when the app is unmounted, it can clean up any reactive scopes
@@ -25,7 +25,18 @@ vide.mount(App) -- works!
 App() -- will error since effect() was not called within a reactive scope
 ```
 
-The reactive graph for the above example:
+Mounting returns a function that when called will destroy any reactive scopes
+created during the `mount()` call.
+
+```lua
+local unmount = mount(App)
+
+unmount()
+```
+
+Vide's reactivity can be represented graphically, as a *reactive graph*.
+
+The reactive graph for the above example looks like so:
 
 ```mermaid
 %%{init: {
@@ -40,10 +51,18 @@ The reactive graph for the above example:
     }
 }}%%
 
-flowchart
+graph
 
-subgraph root
+subgraph root["mount"]
     direction LR
     count --> effect
 end
 ```
+
+When the `mount` scope is destroyed, the `effect` scope will also be destroyed
+since it was created within it.
+
+You don't need to worry about ensuring all your effects are created within a
+root scope, since you should be creating all your UI and corresponding effects
+within a top-level `mount()` call that puts all your UI together. So it is safe
+to assume that any effect you create will be created under this top level scope.