update README.md

README.md

@@ -143,8 +143,7 @@
 
 
 ### Switch Database to mysql [Doc](https://docs.djangoproject.com/en/1.11/ref/databases/)
-    pip install mysqlclient
-
+    pip install PyMySQL==0.7.9
     #edit settings
     import pymysql; 
     pymysql.install_as_MySQLdb()