Update wp-plugin.md (#37636)

There's a grammatical error on https://developer.wordpress.org/block-editor/getting-started/create-block/wp-plugin/#plugin-to-load-script second sentences.

docs/getting-started/create-block/wp-plugin.md

@@ -88,7 +88,7 @@ By default, the build scripts looks for `src/index.js` for the JavaScript file t
 
 ## Plugin to Load Script
 
-To load the built script, so it is run within the editor, you need to tell WordPress about the script. This done in the init action in the `gutenpride.php` file.
+To load the built script, so it is run within the editor, you need to tell WordPress about the script. This is done in the init action in the `gutenpride.php` file.
 
 ```php
 function create_block_gutenpride_block_init() {