Use string for federation_client_minimum_tls_version documentation examples

Signed-off-by: Jan Christian Grünhage <jan.christian@gruenhage.xyz>

Author: jcgruenhage

docs/usage/configuration/config_documentation.md

@@ -1133,14 +1133,14 @@ federation_verify_certificates: false
 
 The minimum TLS version that will be used for outbound federation requests.
 
-Defaults to `1`. Configurable to `1`, `1.1`, `1.2`, or `1.3`. Note
-that setting this value higher than `1.2` will prevent federation to most
-of the public Matrix network: only configure it to `1.3` if you have an
+Defaults to `"1"`. Configurable to `"1"`, `"1.1"`, `"1.2"`, or `"1.3"`. Note
+that setting this value higher than `"1.2"` will prevent federation to most
+of the public Matrix network: only configure it to `"1.3"` if you have an
 entirely private federation setup and you can ensure TLS 1.3 support.
 
 Example configuration:
 ```yaml
-federation_client_minimum_tls_version: 1.2
+federation_client_minimum_tls_version: "1.2"
 ```
 ---
 ### `federation_certificate_verification_whitelist`