update site meta description (#152)

[skip ci]

templates/2xx.html

@@ -4,7 +4,7 @@
   <meta charset='utf-8' >
   <meta name="viewport" content="width=device-width, initial-scale=1" >
   <meta id='theThemeColor' name='theme-color' content='#4169e1' >
-  <meta name="description" content="A mobile-optimized web client for Mastodon." >
+  <meta name="description" content="An alternative web client for Mastodon, focused on speed and simplicity." >
 
   <link rel='manifest' href='/manifest.json' >
   <link id='theFavicon' rel='icon' type='image/png' href='/favicon.png' >