legal: Improve licensing description

Signed-off-by: 林博仁(Buo-ren Lin) <Buo.Ren.Lin@gmail.com>

Author: brlin-tw

README.md

@@ -6,6 +6,17 @@ This project provides a common base of Markdownlint(Node.js variant)'s configura
 
 ## License
 
-This template uses [the Creative Commons Attribution-ShareAlike License, version 4.0](https://creativecommons.org/licenses/by-sa/4.0), or any more recent version of your choice, with an exception of the license only covers the configuration file itself, but not other assets in your project.
+Unless otherwise specified, this product is released with [the Creative Commons Attribution-ShareAlike License, version 4.0](https://creativecommons.org/licenses/by-sa/4.0), or any more recent version of your choice, with an exception of the license only covers the configuration file itself, but not other assets in your project.
 
 For the attribution requirement, please retain the "This file is based on ..." mention and link to this project.
+
+### Identify licenses applicable to a certain product/development asset
+
+If the asset is in plaintext format:
+
+1. Check the `SPDX-License-Identifier` tag in the file's header
+1. Check the [.reuse/dep5](.reuse/dep5) file from the source tree/release tree directory
+
+If the asset is not in plaintext format:
+
+Check the [.reuse/dep5](.reuse/dep5) file from the source tree/release tree directory