Added air gap to the documentation word list

doc/.vale/gitlab/SubstitutionWarning.yml

@@ -11,6 +11,7 @@ link: https://about.gitlab.com/handbook/communication/#top-misused-terms
 level: warning
 ignorecase: true
 swap:
+  air(?:-| )?gapped: offline environment
   click: select
   code base: codebase
   config: configuration

doc/development/documentation/styleguide/word_list.md

@@ -97,6 +97,12 @@ The token generated when you create an agent for Kubernetes. Use **agent access
 - secret token
 - authentication token
 
+## air gap, air-gapped
+
+Use **offline environment** to describe installations that have physical barriers or security policies that prevent or limit internet access. Do not use **air gap**, **air gapped**, or **air-gapped**. For example:
+
+- The firewall policies in an offline environment prevent the computer from accessing the internet.
+
 ## allow, enable
 
 Try to avoid **allow** and **enable**, unless you are talking about security-related features.