fix(meta): add missing router.base prefix to favicon (#354)

* Relative path missing for the favicon

The favicon must be accessible from any page and it does not matter how deep the page is. The only possible solution is to use a relative url.

* Update module.js

Co-authored-by: pooya parsa <pyapar@gmail.com>

lib/meta/module.js

@@ -111,7 +111,7 @@ function generateMeta (pwa) {
   if (options.favicon && !find(this.options.head.link, 'rel', 'shortcut icon') && existsSync(favicon)) {
     console.warn('You are using a low quality icon, use icon png. See https://pwa.nuxtjs.org/icon/')
 
-    this.options.head.link.push({ rel: 'shortcut icon', href: 'favicon.ico' })
+    this.options.head.link.push({ rel: 'shortcut icon', href: this.options.router.base + 'favicon.ico' })
   }
 
   // Title