I've created a Custom Deployer for Web 8 and have built a custom .jar file. I've added it to the cd_storage config file and want to know which folder I should deploy the .jar to:
As all of the specific deployer classes (Processor, ComponentDeployer, etc.) remain in the micro-service folder (and still are old fashioned "com.tridion..."); I would put it in there, but I think that it doesn't mind as some of the classes used by the deployer-service, are located in the lib folder.
You can indeed place it into any subfolder within the services folder. I recommend creating a new folder called deployer-extensions or similar in order that it makes upgrading easier.
You will need to reinstall the service if you want the new folder to be added to the class path.