add secret to glossary

_data/glossary/secret.yml

@@ -0,0 +1,14 @@
+id: secret
+name: Secret
+full-link: /docs/concepts/configuration/secret/
+related:
+- pods
+- volume
+tags:
+- core-object
+- security
+short-description: >
+  stores sensitive information, such as passwords, OAuth tokens, and ssh keys.
+long-description: >
+  Sensetive information stored in a Secret allows for more control over how it is used and reduces the risk of accidental exposure. 
+  A {% glossary_tooltip text="Pod" term_id="pod" %} references the secret as a file in a {% glossary_tooltip text="Volume" term_id="volume" %} mount or by the kubelet pulling images for a pod.