Auto-generate sample config file

This PS auto-generates the sample config file using
oslo-config-generator which is how every project should reliably
produce a config file.

In addition, the Patrole documentation was updated to link to the
generated config file, so that the documentation accurately
shows config options.

Change-Id: Ib3c39084b4c2b5a0078d1293d882cf9a9050b29b
Closes-Bug: #1709490
diff --git a/etc/config-generator.patrole.conf b/etc/config-generator.patrole.conf
new file mode 100644
index 0000000..8988ae0
--- /dev/null
+++ b/etc/config-generator.patrole.conf
@@ -0,0 +1,3 @@
+[DEFAULT]
+output_file = etc/patrole.conf.sample
+namespace = patrole.config