node-SDK: Change hfc Peer constructor description

There are two incomplete descriptions.  "config" should be
"configuration" and the url description is incomplete.
Fix parameter chain and add parameter pem with description.
https://jira.hyperledger.org/browse/FAB-233

Change-Id: I82e678abcc26bacfb48b712dd35b47f9647f6b3a
Signed-off-by: Caroline Daughtrey <cdaughtr@us.ibm.com>

sdk/node/src/hfc.ts

@@ -2039,9 +2039,13 @@ export class Peer {
     private peerClient:any;
 
     /**
-     * Constructor for a peer given the endpoint config for the peer.
-     * @param {string} url The URL of
-     * @param {Chain} The chain of which this peer is a member.
+     * Constructs a Peer given its endpoint configuration settings
+     * and returns the new Peer.
+     * @param {string} url The URL with format of "grpcs://host:port".
+     * @param {Chain} chain The chain of which this peer is a member.
+     * @param {string} pem The certificate file, in PEM format,
+     * to use with the gRPC protocol (that is, with TransportCredentials).
+     * Required when using the grpcs protocol.
      * @returns {Peer} The new peer.
      */
     constructor(url:string, chain:Chain, pem:string) {