docs(security): document max header size

Author: JoergSiebahn

docs/security/index.md

@@ -51,11 +51,7 @@ Prometheus metrics are exposed as expected by SDA environments.
 
 ## Risk: Buffer Overflow
 
-**TODO** check others then input header limit
-
-## Risk: Man-in-the-Middle
-
-**TODO** check cookie secure flag
+The size request and response headers is limited to 8KiB.
 
 ## Header