Add a Cancel button and close buttonin API Documentation Manage dialogue

[Nazarah]

If user opens the Manage dialogue under API documentation and doesn't do any action afterwords, only Save button is available to close the dialogue.
Here user might thing he is actually saving something new, where actually nothing new is getting updates.
Sol: Add a Cancel button at the left side of Save button.
On opening the dialogue, the Cancel button should be focused.
Also Add a close button at top right corner of the dialogue