Reverted first part of [... / Key blocks] change

Author: Benkex

content/tutorial/02-advanced-svelte/02-transitions/08-key-blocks/README.md

@@ -2,7 +2,7 @@
 title: Key blocks
 ---
 
-Key blocks destroy and recreate their contents when the value of the following expression (in the example: `i`) changes. This is useful if you want an element to play its transition whenever a value changes instead of only when the element enters or leaves the DOM.
+Key blocks destroy and recreate their contents when the value of an expression changes. This is useful if you want an element to play its transition whenever a value changes instead of only when the element enters or leaves the DOM.
 
 Here, for example, we'd like to play the `typewriter` transition from `transition.js` whenever the loading message, i.e. `i` changes. Wrap the `<p>` element in a key block: