Simplify the example config

I never meant for people to copy and paste this example---it's redundant and
probably wrong---but lots of people do! Removing a few weird options makes the
example clearer, I think, and will result in less-strange initial configs for
people who do copy & paste.

docs/guides/main.rst

@@ -137,7 +137,7 @@ favorite text editor. The file will start out empty, but here's good
 place to start::
 
     directory: ~/music
-    library: ~/data/musiclibrary.blb
+    library: ~/data/musiclibrary.db
 
 Change that first path to a directory where you'd like to keep your music. Then,
 for ``library``, choose a good place to keep a database file that keeps an index

docs/reference/config.rst

@@ -814,21 +814,14 @@ Example
 
 Here's an example file::
 
-    library: /var/music.blb
     directory: /var/mp3
     import:
         copy: yes
         write: yes
-        resume: ask
-        quiet_fallback: skip
-        timid: no
         log: beetslog.txt
-    ignore: .AppleDouble ._* *~ .DS_Store
-    ignore_hidden: yes
     art_filename: albumart
     plugins: bpd
     pluginpath: ~/beets/myplugins
-    threaded: yes
     ui:
         color: yes