docs(README): Write References section

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

Author: brlin-tw

README.md

@@ -38,6 +38,13 @@ Refer to the following instructions to run the conversion script:
 
    The converted Markdown content will be saved to the specified output file.
 
+## References
+
+The following materials are referenced during the development of this product:
+
+* [Beautiful Soup Documentation](https://www.crummy.com/software/BeautifulSoup/bs4/doc/)  
+  Explains how to use the Beautiful Soup library for parsing HTML data.
+
 ## Licensing
 
 Unless otherwise noted([comment headers](https://reuse.software/spec-3.3/#comment-headers)/[REUSE.toml](https://reuse.software/spec-3.3/#reusetoml)), this product is licensed under [the 3.0 version of the Affero General Public License](https://www.gnu.org/licenses/agpl-3.0.html), or any of its more recent versions of your preference.