Fixed typo (#347)

Author: neufeldtech

docs/index.asciidoc

@@ -284,7 +284,7 @@ database timezone is UTC then you do not need to set either of these settings.
   * Value type is <<string,string>>
   * There is no default value for this setting.
 
-JDBC driver class to load, for exmaple, "org.apache.derby.jdbc.ClientDriver"
+JDBC driver class to load, for example, "org.apache.derby.jdbc.ClientDriver"
 NB per https://github.com/logstash-plugins/logstash-input-jdbc/issues/43 if you are using
 the Oracle JDBC driver (ojdbc6.jar) the correct `jdbc_driver_class` is `"Java::oracle.jdbc.driver.OracleDriver"`