Remove tutorial comments

var/spack/repos/builtin/packages/xerces-c/package.py

@@ -1,19 +1,3 @@
-# FIXME:
-# This is a template package file for Spack.  We've conveniently
-# put "FIXME" labels next to all the things you'll want to change.
-#
-# Once you've edited all the FIXME's, delete this whole message,
-# save this file, and test out your package like this:
-#
-#     spack install xerces-c
-#
-# You can always get back here to change things with:
-#
-#     spack edit xerces-c
-#
-# See the spack documentation for more information on building
-# packages.
-#
 from spack import *
 
 class XercesC(Package):