docs: expand explanation of timezone option

closes #620
closes #1680

Author: dougwilson

Readme.md

@@ -192,7 +192,7 @@ When establishing a connection, you can set the following options:
 * `charset`: The charset for the connection. This is called "collation" in the SQL-level
   of MySQL (like `utf8_general_ci`). If a SQL-level charset is specified (like `utf8mb4`)
   then the default collation for that charset is used. (Default: `'UTF8_GENERAL_CI'`)
-* `timezone`: The timezone used to store local dates. (Default: `'local'`)
+* `timezone`: The timezone configured on the MySQL server. This is used to type cast server date/time values to JavaScript `Date` object and vice versa. This can be `'local'`, `'Z'`, or an offset in the form `+HH:MM` or `-HH:MM`. (Default: `'local'`)
 * `connectTimeout`: The milliseconds before a timeout occurs during the initial connection
   to the MySQL server. (Default: `10000`)
 * `stringifyObjects`: Stringify objects instead of converting to values. See