Document that blog_name changes the navbar (alshedivat#89)

Author: jkmacc-LANL

_config.yml

@@ -55,7 +55,7 @@ google_analytics: UA-XXXXXXXXX # out your google-analytics code
 # Blog
 # -----------------------------------------------------------------------------
 
-blog_name: al-folio
+blog_name: al-folio  # your blog must have a name for it to show up in the nav bar
 blog_description: a simple whitespace theme for academics
 permalink: /blog/:year/:title/