Put the notice for rules in comment block

This comment block marked by `@notice` is picked up by automation and included
in the Kibana NOTICE.txt that we ship with the tar.gz.

Follow up for #56090.

x-pack/legacy/plugins/siem/server/lib/detection_engine/rules/prepackaged_rules/notice.ts

@@ -0,0 +1,36 @@
+/* eslint-disable @kbn/eslint/require-license-header */
+
+/* @notice
+ * This product bundles rules based on https://github.com/BlueTeamLabs/sentinel-attack
+ * which is available under a "MIT" license. The files based on this license are:
+ *
+ * - windows_defense_evasion_via_filter_manager.json
+ * - windows_process_discovery_via_tasklist_command.json
+ *- windows_priv_escalation_via_accessibility_features.json
+ *- windows_persistence_via_application_shimming.json
+ *- windows_execution_via_trusted_developer_utilities.json
+ *- windows_execution_via_net_com_assemblies.json
+ *- windows_execution_via_connection_manager.json
+ *
+ * MIT License
+ *
+ * Copyright (c) 2019 Edoardo Gerosa, Olaf Hartong
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is furnished to do
+ * so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */