We add the instancename parameter documentation for oci8 driver

Change the name of the parameter instance_name by instancename

Hello, first sorry for my English. 
I need to put in the ORACLE Connection string to the parameter: (INSTANCE_NAME = XXXXX) 

I was reading the source code at github and the latest version does not include this possibility in the method getEasyConnectString. 

Could add to the next version an element in the array of parameters, eg $params['instance_name'] and concatenating that value to the Connection string? 

Thank you, greetings 
Facundo Panizza

[DBAL-813] Original PDOException is preserved

Fix typo and formatting in security docs

Add automatic platform version detection

Applying patch suggested by @guilhermeblanco for SQLite's auto-inc integer PKs

See symfony/symfony#10238

Add close() method in MasterSlaveConnection.php

Added support for column collation

Fix sqlite autoincrement detection