Merge pull request sveltejs#3955 from joncfoo/patch-1

Document $: in the tutorial

Author: Rich-Harris

site/content/tutorial/02-reactivity/02-reactive-declarations/text.md

@@ -11,12 +11,12 @@ let count = 0;
 $: doubled = count * 2;
 ```
 
-> Don't worry if this looks a little alien. It's valid (if unconventional) JavaScript, which Svelte interprets to mean 're-run this code whenever any of the referenced values change'. Once you get used to it, there's no going back.
+> Don't worry if this looks a little alien. It's [valid](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/label) (if unconventional) JavaScript, which Svelte interprets to mean 're-run this code whenever any of the referenced values change'. Once you get used to it, there's no going back.
 
 Let's use `doubled` in our markup:
 
 ```html
 <p>{count} doubled is {doubled}</p>
 ```
 
-Of course, you could just write `{count * 2}` in the markup instead — you don't have to use reactive values. Reactive values become particularly valuable when you need to reference them multiple times, or you have values that depend on *other* reactive values.
+Of course, you could just write `{count * 2}` in the markup instead — you don't have to use reactive values. Reactive values become particularly valuable when you need to reference them multiple times, or you have values that depend on *other* reactive values.