etcdmain: update -ca-file description

so people could deprecate old flags and use new flags much easier.

Documentation/configuration.md

@@ -133,7 +133,7 @@ To start etcd automatically using custom settings at startup in Linux, using a [
 The security flags help to [build a secure etcd cluster][security].
 
 ##### -ca-file [DEPRECATED]
-+ Path to the client server TLS CA file.
++ Path to the client server TLS CA file. `-ca-file ca.crt` could be replaced by `-trusted-ca-file ca.crt -client-cert-auth` and etcd will perform the same.
 + default: none
 
 ##### -cert-file
@@ -153,7 +153,7 @@ The security flags help to [build a secure etcd cluster][security].
 + default: none
 
 ##### -peer-ca-file [DEPRECATED]
-+ Path to the peer server TLS CA file.
++ Path to the peer server TLS CA file. `-peer-ca-file ca.crt` could be replaced by `-peer-trusted-ca-file ca.crt -peer-client-cert-auth` and etcd will perform the same.
 + default: none
 
 ##### -peer-cert-file

etcdmain/help.go

@@ -87,7 +87,7 @@ proxy flags:
 security flags:
 
 	--ca-file '' [DEPRECATED]
-		path to the client server TLS CA file.
+		path to the client server TLS CA file. '-ca-file ca.crt' could be replaced by '-trusted-ca-file ca.crt -client-cert-auth' and etcd will perform the same.
 	--cert-file ''
 		path to the client server TLS cert file.
 	--key-file ''
@@ -97,7 +97,7 @@ security flags:
 	--trusted-ca-file ''
 		path to the client server TLS trusted CA key file.
 	--peer-ca-file '' [DEPRECATED]
-		path to the peer server TLS CA file.
+		path to the peer server TLS CA file. '-peer-ca-file ca.crt' could be replaced by '-peer-trusted-ca-file ca.crt -peer-client-cert-auth' and etcd will perform the same.
 	--peer-cert-file ''
 		path to the peer server TLS cert file.
 	--peer-key-file ''