[fix/docs] Remove invalid statement in onMount tutorial

Removes an old reference in the onMount tutorial as the reference has been moved to the advanced section and is no longer before this part.

site/content/tutorial/07-lifecycle/01-onmount/text.md

@@ -4,7 +4,7 @@ title: onMount
 
 Every component has a *lifecycle* that starts when it is created, and ends when it is destroyed. There are a handful of functions that allow you to run code at key moments during that lifecycle.
 
-The one you'll use most frequently is `onMount`, which runs after the component is first rendered to the DOM. We briefly encountered it [earlier](/tutorial/bind-this) when we needed to interact with a `<canvas>` element after it had been rendered.
+The one you'll use most frequently is `onMount`, which runs after the component is first rendered to the DOM.
 
 We'll add an `onMount` handler that loads some data over the network:
 
@@ -25,4 +25,4 @@ We'll add an `onMount` handler that loads some data over the network:
 
 Lifecycle functions must be called while the component is initialising so that the callback is bound to the component instance — not (say) in a `setTimeout`.
 
-If the `onMount` callback returns a function, that function will be called when the component is destroyed.
+If the `onMount` callback returns a function, that function will be called when the component is destroyed.