Update docs about when incoming connections are served

docs/ENVIRONMENT.rst

@@ -92,12 +92,18 @@ These environment variables are optional:
 
   If set ElectrumX will serve TCP clients on **HOST**:**TCP_PORT**.
 
+  **Note**: ElectrumX will not serve TCP connections until it has
+  fully caught up with your daemon.
+
 * **SSL_PORT**
 
   If set ElectrumX will serve SSL clients on **HOST**:**SSL_PORT**.
   If set then SSL_CERTFILE and SSL_KEYFILE must be defined and be
   filesystem paths to those SSL files.
 
+  **Note**: ElectrumX will not serve SSL connections until it has
+  fully caught up with your daemon.
+
 * **RPC_HOST**
 
   The host or IP address that the RPC server will listen on and

docs/HOWTO.rst

@@ -256,6 +256,10 @@ machine.  **DB_CACHE** set to 1,800.  LevelDB.
 For chains other than bitcoin-mainnet sychronization should be much
 faster.
 
+**Note**: ElectrumX will not serve normal client connections until it
+has fully synchronized and caught up with your daemon.  However
+LocalRPC connections are served at all times.
+
 
 Terminating ElectrumX
 =====================