docs: fix typos in addons/ (#72)

Author: GeopJr

Diff for: addons/use.md

@@ -1,6 +1,6 @@
 # Use Addon
 
-Addons are sets of additionnal components, layouts, styles, configuration...etc. that you can use in your presentation.
+Addons are sets of additional components, layouts, styles, configuration...etc. that you can use in your presentation.
 
 They are quite similar to [themes](/themes/use), but in general:
 

Diff for: addons/write-an-addon.md

@@ -14,7 +14,7 @@ An addon can contribute to the following points:
 
 ## Conventions
 
-Adons are published to npm registry, and they should follow the conventions below:
+Addons are published to npm registry, and they should follow the conventions below:
 
 - Package name should start with `slidev-addon-`, for example: `slidev-addon-awesome`
 - Add `slidev-addon` and `slidev` in the `keywords` field of your `package.json`
@@ -49,7 +49,7 @@ And optionally, you can also add some scripts to your `packages.json`
 }
 ```
 
-To publish your theme, simply run `npm publish` and you are good to go. There is no build process required (which means you can directly publish `.vue` and `.ts` files, Slidev is smart enough to understand them).
+To publish your addon, simply run `npm publish` and you are good to go. There is no build process required (which means you can directly publish `.vue` and `.ts` files, Slidev is smart enough to understand them).
 
 Addon contribution points follow the same conventions as local customization, please refer to [the docs for the naming conventions](/custom/).