Add tls versions

Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>

Author: Julien Pivotto

https/README.md

@@ -1,7 +1,10 @@
 # HTTPS Package for Prometheus
 
-The `https` directory contains a Go package and a sample configuration file for running `node_exporter` with HTTPS instead of HTTP.
-When running a server with TLS use the flag `--web.config`
+The `https` directory contains a Go package and a sample configuration file for
+running `node_exporter` with HTTPS instead of HTTP. We currently support TLS 1.3
+and TLS 1.2.
+
+To run a server with TLS, use the flag `--web.config`.
 
 e.g. `./node_exporter --web.config="web-config.yml"`
 If the config is kept within the https directory.