docs(driver): add clarification note to DaffInMemoryDriverBase#url (#3176)

Author: griest024

libs/driver/in-memory/src/driver/base.class.ts

@@ -6,6 +6,7 @@ import { InMemoryBackendConfigArgs } from 'angular-in-memory-web-api';
 export abstract class DaffInMemoryDriverBase {
   /**
    * The URL of the corresponding backend.
+   * Does not include a trailing slash, it is of the form: `/<api base>/<collection name>`.
    */
   protected readonly url = `/${this.config.apiBase}/${this.collectionName}`;