fix "troubleshooting" section in puppet

The "debugging things" title wasn't great, and we use
"troubleshooting" elsewhere anyways.

Also add headings to make this long section a bit more readable.

howto/puppet.md

@@ -474,7 +474,9 @@ argument from Hiera. This is how the transition to a managed
     operate a change. You can then examine the output and see if the
     change is legitimate or abort the configuration change.
 
-## Debugging things
+## Troubleshooting
+
+### Running Puppet by hand and logging
 
 When a Puppet manifest is not behaving as it should, the first step is
 to run it by hand on the host: