fix indefinite articles

Author: keithamus

tutorials/mastodon-toot-embed/index.md

@@ -13,7 +13,7 @@ Our aim will be to create a `<toot-embed>` element will allow users to share and
 "toots") from the Mastodon social network, and will include features such as the ability to show or hide the user handle
 and avatar image, as well as the option to customize the appearance of the toot.
 
-Here's a example of a Mastodon toot embed. We'll be making something similar.
+Here's an example of a Mastodon toot embed. We'll be making something similar.
 
 <iframe src="https://fosstodon.org/@webcomponentsguide/109660552894549193/embed" class="mastodon-embed" style="max-width: 100%; border: 0" width="400" allowfullscreen="allowfullscreen"></iframe><script src="https://fosstodon.org/embed.js" async="async"></script>
 

tutorials/mastodon-toot-embed/properties-and-methods.md

@@ -57,7 +57,7 @@ class TootEmbedElement extends HTMLElement {
 TootEmbedElement.define()
 ```
 
-And we can persist the value to a attribute using `setAttribute`:
+And we can persist the value to an attribute using `setAttribute`:
 
 ```js
 class TootEmbedElement extends HTMLElement {