Merge pull request #1824 from rubocop/add-document

Add document for Department

Author: bquorning

docs/modules/ROOT/nav.adoc

@@ -1,6 +1,7 @@
 * xref:index.adoc[Home]
 * xref:installation.adoc[Installation]
 * xref:usage.adoc[Usage]
+* xref:departments.adoc[Departments]
 * xref:cops.adoc[Cops]
 * xref:upgrade_to_version_2.adoc[Upgrade to 2.x]
 * xref:third_party_rspec_syntax_extensions.adoc[RSpec syntax extensions in third-party gems]