docs(plugins): add a one-line description to each extension point

app/scripts/modules/core/src/plugins/deck.plugin.ts

@@ -5,17 +5,20 @@ import { Registry } from 'core/registry';
 import { SearchResultType, searchResultTypeRegistry } from 'core/search';
 
 export interface IDeckPlugin {
+  /** Custom Stage UI (configuration and execution details) */
   stages?: IStageTypeConfig[];
+  /** Custom Preconfigured Job Stage UI (configuration and execution details) */
   preconfiguredJobStages?: IStageTypeConfig[];
+  /** Help Text for use in <HelpField /> */
   help?: { [helpKey: string]: string };
+  /** Custom global search types */
   search?: SearchResultType[];
 
   initialize?(plugin: IDeckPlugin): void;
 }
 
-/** Given a plugin, registers the plugin's extensions */
+/** Given a plugin, registers the plugin's extensions with Deck registries */
 export function registerPluginExtensions(plugin: IDeckPlugin): PromiseLike<any> {
-  // Register the plugin's extensions with deck.
   plugin.stages?.forEach(stage => Registry.pipeline.registerStage(stage));
   plugin.preconfiguredJobStages?.forEach(stage => Registry.pipeline.registerPreconfiguredJobStage(stage));
   toPairs(plugin.help ?? {}).forEach(([key, value]) => HelpContentsRegistry.register(key, value));