fix typo in import of "@webext-core/messaging" installation docs (#95)

Author: cvan

docs/content/messaging/0.installation.md

@@ -164,7 +164,7 @@ Here, we're injecting a script, initializing it with data, and allowing the scri
 ::code-group
 
 ```ts [Content Script]
-import { websiteMessenger } from './website-messenging';
+import { websiteMessenger } from './website-messaging';
 
 const script = document.createElement('script');
 script.src = browser.runtime.getURL('/path/to/injected.js');
@@ -180,7 +180,7 @@ websiteMessenger.onMessage('somethingHappened', (data) => {
 ```
 
 ```ts [Injected script]
-import { websiteMessenger } from './website-messenging';
+import { websiteMessenger } from './website-messaging';
 
 websiteMessenger.onMessage('init', data => {
   // initialize injected script