Add a security policy file and a corresponding section to README (#263)

A security policy (typically a SECURITY.md file) can give users
information about what constitutes a vulnerability and how to report one
securely so that information about a bug is not publicly visible.

README.md

@@ -377,3 +377,7 @@ Then execute `python -m build python/` to create a whl from the sources. It can
 - ***Spark’s groupByKey should be avoided – and here’s why**, Enrico Minack, 13/06/2023*:<br/>https://www.gresearch.com/blog/article/sparks-groupbykey-should-be-avoided-and-heres-why/
 - ***Inspecting Parquet files with Spark**, Enrico Minack, 28/07/2023*:<br/>https://www.gresearch.com/blog/article/parquet-files-know-your-scaling-limits/
 - ***Enhancing Spark’s UI with Job Descriptions**, Enrico Minack, 12/12/2023*:<br/>https://www.gresearch.com/blog/article/enhancing-sparks-ui-with-job-descriptions/
+
+## Security
+
+Please see our [security policy](https://github.com/G-Research/spark-extension/blob/master/SECURITY.md) for details on reporting security vulnerabilities.

SECURITY.md

@@ -0,0 +1,5 @@
+# Security and Coordinated Vulnerability Disclosure Policy
+
+This project appreciates and encourages coordinated disclosure of security vulnerabilities. We prefer that you use the GitHub reporting mechanism to privately report vulnerabilities. Under the main repository's security tab, click "Report a vulnerability" to open the advisory form.
+
+If you are unable to report it via GitHub, have received no response after repeated attempts, or have other security related questions, please contact [email protected] and mention this project in the subject line.