lynis: add page (#3034)

pages/linux/lynis.md

@@ -0,0 +1,16 @@
+# lynis
+
+> System and security auditing tool.
+> Documentation: <https://cisofy.com/documentation/lynis/>.
+
+- Check that Lynis is up-to-date:
+
+`sudo lynis update info`
+
+- Run a security audit of the system:
+
+`sudo lynis audit system`
+
+- Run a security audit of a Dockerfile:
+
+`sudo lynis audit dockerfile {{path/to/dockerfile}}`