fix(docs): correct TLS config key from [tls] to [server.tls]

Author: farhan-syah

docs/administration/authentication.rdx

@@ -52,7 +52,7 @@ Supported algorithms: RS256, ES256.
 ## mTLS
 
 ```toml
-[tls]
+[server.tls]
 cert = "/path/to/server.crt"
 key = "/path/to/server.key"
 client_ca = "/path/to/ca.crt"     # enables mTLS

docs/administration/tls.rdx

@@ -27,7 +27,7 @@ ilp = false    # disable TLS for high-throughput ILP ingest
 ## mTLS (Mutual TLS)
 
 ```toml
-[tls]
+[server.tls]
 cert = "/path/to/server.crt"
 key = "/path/to/server.key"
 client_ca = "/path/to/ca.crt"