resolves #1438: Add SECURITY.md (#1440)

### Summary
> Describe your changes.

Adds a security policy.

### Related issues or links
> Include links to relevant issues or other pages.

- #1438

Credit to https://github.com/falcosecurity/falco/security where I
plagiarized the text from. I think it accomplishes what we need it to
without introducing heavyweight process that we aren't ready for.

Signed-off-by: Alex Chantavy <[email protected]>

Author: achantavy

SECURITY.md

@@ -0,0 +1,12 @@
+# Security Policy
+Cartography is a security tool, and its community of course takes security very seriously.
+
+We appreciate your efforts to disclose your findings responsibly and will make every effort to acknowledge your contributions.
+
+## Supported versions
+Security updates will typically only be applied to the latest release (at least until Cartography reaches the first stable major version).
+
+## Reporting a vulnerability
+To report a security issue, email [email protected] and include the word "SECURITY" in the subject line.
+
+Maintainers will send a response indicating the next steps in handling your report. After the initial reply to your report, we will keep you informed of the progress towards a fix and full announcement and may ask for additional information or guidance.