Update MySQL docs.

Author: alexmacarthur

mysql/README.md

@@ -21,3 +21,10 @@ While inside the shell, run the following:
 ```
 CREATE DATABASE mydatabase;
 ```
+## Using SequelPro?
+
+You might get a `Authentication plugin 'caching_sha2_password' cannot be loaded` error. If that's the case, [enter the MySQL shell](#enter-the-mysql-shell) and run the following command: 
+
+```mysql
+ALTER USER 'root'@'%' IDENTIFIED WITH mysql_native_password BY 'password'
+```