Added feature-gate to glossary (#38895)

* Added feature-gates into glossary

* Update content/en/docs/reference/glossary/feature-gates.md

Co-authored-by: divya-mohan0209 <[email protected]>

* incorporated the suggestions for: glossary term feature gate

* Incorporated review comments

* Incorporated review comments

* Update content/en/docs/reference/glossary/feature-gates.md

Co-authored-by: divya-mohan0209 <[email protected]>

Co-authored-by: divya-mohan0209 <[email protected]>

Author: T-Lakshmi

content/en/docs/reference/glossary/feature-gates.md

@@ -0,0 +1,23 @@
+---
+title: Feature gate
+id: feature-gate
+date: 2023-01-12
+full_link: /docs/reference/command-line-tools-reference/feature-gates/
+short_description: >
+  A way to control whether or not a particular Kubernetes feature is enabled.
+
+aka: 
+tags:
+- fundamental
+- operation
+---
+
+Feature gates are a set of keys (opaque string values) that you can use to control which
+Kubernetes features are enabled in your cluster.
+
+<!--more-->
+
+You can turn these features on or off using the `--feature-gates` command line flag on each Kubernetes component.
+Each Kubernetes component lets you enable or disable a set of feature gates that are relevant to that component.
+The Kubernetes documentation lists all current 
+[feature gates](/docs/reference/command-line-tools-reference/feature-gates/) and what they control.