Path to example files incorrect

[Josh Holland]

This is a regression of https://launchpad.net/bugs/794493.

The example files in /usr/share/doc/drush are not detected by the code in /usr/share/php/drush/includes/bootstrap.inc because README.md is compressed and named README.md.gz.

ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: drush 5.10.0-2
ProcVersionSignature: Ubuntu 3.16.0-21.28-generic 3.16.4
Uname: Linux 3.16.0-21-generic x86_64
ApportVersion: 2.14.7-0ubuntu5
Architecture: amd64
CurrentDesktop: Unity
Date: Mon Oct 13 12:09:34 2014
InstallationDate: Installed on 2014-07-17 (88 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
PackageArchitecture: all
SourcePackage: drush
UpgradeStatus: Upgraded to utopic on 2014-10-10 (2 days ago)