pass plugin to uninstall

docs/development/plugin-triggers.md

@@ -869,7 +869,7 @@ some code to remove a docker hub tag because it's not implemented in the CLI....
 ### `uninstall`
  - Description: Used to cleanup after itself.
  - Invoked by: `dokku plugin:uninstall`
- - Arguments: None
+ - Arguments: `$PLUGIN`
  - Example:
 
  ```shell
@@ -878,7 +878,9 @@ some code to remove a docker hub tag because it's not implemented in the CLI....
 
  set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
 
- docker rmi -f "${PLUGIN_IMAGE_DEPENDENCY}"
+ PLUGIN="$1"
+
+ [[ "$PLUGIN" = "my-plugin" ]] && docker rmi -f "${PLUGIN_IMAGE_DEPENDENCY}"
  ```
 
 ### `update`

plugins/plugin/functions

@@ -70,7 +70,7 @@ uninstall_plugin() {
   local PLUGIN="$1"
   [[ -e $PLUGIN_CORE_AVAILABLE_PATH/$PLUGIN ]] && dokku_log_fail "Cannot uninstall a core plugin"
   [[ ! -e $PLUGIN_AVAILABLE_PATH/$PLUGIN ]] && dokku_log_fail "Plugin ($PLUGIN) is not currently installed"
-  plugn trigger uninstall
+  plugn trigger uninstall "$PLUGIN"
   plugn uninstall "$PLUGIN"
   dokku_log_info1_quiet "Plugin $PLUGIN uninstalled"
 }