Use title case

Author: marcphilipp

SECURITY.md

@@ -2,7 +2,7 @@
 
 [![OpenSSF Best Practices](https://www.bestpractices.dev/projects/9607/badge)](https://www.bestpractices.dev/projects/9607) [![OpenSSF Scorecard](https://api.scorecard.dev/projects/github.com/junit-team/junit5/badge)](https://scorecard.dev/viewer/?uri=github.com/junit-team/junit5)
 
-## JAR signing
+## JAR Signing
 
 JUnit JARs released on Maven Central are signed.
 You'll find more information about the key here: [KEYS](./KEYS)