Merge pull request #6991 from jzohrab/debugging_docs

Add debugging log docs.

website/source/docs/other/debugging.html.md

@@ -57,3 +57,9 @@ option. For example:
 ```
 $ vagrant up --debug
 ```
+
+Redirect the log output using `&>` to capture both stdout and stderr:
+
+```
+$ vagrant up --provision --debug &> vagrant.log
+```