docs: improve wording on Your First Component page

Replace 'lets' with 'allows' and add Oxford comma in 'rich,
structured documents' for clearer, more formal prose.

Fixes #7269

Author: cursoragent

src/content/learn/your-first-component.md

@@ -18,7 +18,7 @@ title: Your First Component
 
 ## Components: UI building blocks {/*components-ui-building-blocks*/}
 
-On the Web, HTML lets us create rich structured documents with its built-in set of tags like `<h1>` and `<li>`:
+On the Web, HTML allows us to create rich, structured documents with its built-in set of tags like `<h1>` and `<li>`:
 
 ```html
 <article>