Address comments:

  - lib/auth/auth.js :
      write some JSdoc for `function generateV4Headers` and
      `function doAuth`

lib/auth/auth.js

@@ -93,6 +93,16 @@ function extractParams(request, log, awsService, data) {
     return { err: null, params: publicUserInfo };
 }
 
+/**
+ * This function will check validity of request parameters to authenticate
+ *
+ * @param {Http.Request} request - Http request object
+ * @param {object} log - Logger object
+ * @param {function} cb - the callback
+ * @param {string} awsService - Aws service related
+ * @param {RequestContext} requestContext - an instance of a RequestContext
+ * @return {undefined}
+ */
 function doAuth(request, log, cb, awsService, requestContext) {
     const res = extractParams(request, log, awsService, request.query);
     if (res.err) {
@@ -121,6 +131,18 @@ function doAuth(request, log, cb, awsService, requestContext) {
     return cb(errors.InternalError);
 }
 
+
+/**
+ * This function will generate a version 4 header
+ *
+ * @param {Http.Request} request - Http request object
+ * @param {object} data - Parameters from queryString parsing or body of
+ *                        POST request
+ * @param {string} accessKey - the accessKey
+ * @param {string} secretKeyValue - the secretKey
+ * @param {string} awsService - Aws service related
+ * @return {undefined}
+ */
 function generateV4Headers(request, data, accessKey, secretKeyValue,
                            awsService) {
     Object.assign(request, { headers: {} });