To get started with development include a copy of the Oxide.Ext.Discord.dll with your project assembly references. The Discord Extension has XML documentation that allows your IDE to see information about methods and fields from the extension. If you would like to see this extra information you can include the Oxide.Ext.Discord.xml in the same directory as the Discord Extension DLL
The discord API is constantly changing and requires constant updates to stay update to date with the changes. For the discord extension we will be releasing monthly updates containing all changes for the given period. If you would like to see a feature released before the monthly release please open a request on uMod and it will be updated time permitting.