Fix instructions for running tests in Readme.md: the variables were not being exported to the make test process

Author: marcuswestin

Readme.md

@@ -877,7 +877,7 @@ For example, if you have an installation of mysql running on localhost:3306 and
 
 ```
   mysql -u root -e "CREATE DATABASE IF NOT EXISTS node_mysql_test"
-  MYSQL_HOST=localhost && MYSQL_PORT=3306 && MYSQL_DATABASE=node_mysql_test && MYSQL_USER=root && MYSQL_PASSWORD= && make test
+  MYSQL_HOST=localhost MYSQL_PORT=3306 MYSQL_DATABASE=node_mysql_test MYSQL_USER=root MYSQL_PASSWORD= make test
 ```
 
 ## Todo