gh-ssh-key: add page (#5308)

pages/common/gh-ssh-key.md

@@ -0,0 +1,20 @@
+# gh ssh-key
+
+> Manage GitHub SSH keys from the command line.
+> More information: <https://cli.github.com/manual/gh_ssh-key>.
+
+- Display help:
+
+`gh ssh-key`
+
+- List SSH keys for the currently authenticated user:
+
+`gh ssh-key list`
+
+- Add an SSH key to the currently authenticated user's account:
+
+`gh ssh-key add {{path/to/key.pub}}`
+
+- Add an SSH key to the currently authenticated user's account with a specific title:
+
+`gh ssh-key add --title {{title}} {{path/to/key.pub}}`