An Apps Script project uses a manifest file to configure certain details about the script and its operation. To learn how to view and edit a manifest, see Manifests.
This documentation covers the details of configuring a manifest for a Editor Add-on.
Manifest structure for editor add-ons
The Apps Script manifest structure doesn't include any properties that are specific to editor add-ons. However, editor add-on manifests can define the general properties that are common to all Apps Script projects, such as OAuth scopes and library dependencies.
See Manifest structure for a full list of potential manifest properties that editor add-ons can use.