Rephrase that following generic PDO attributes may not be implemented

[gogromat]

From manual page: https://php.net/pdo.getattribute

--- " The generic attributes that apply to database connections are as follows"

should be rephrased as "may apply" as they are not necessarily implemented.

Ex.: lists PDO::ATTR_TIMEOUT although it's not implemented for SQL Server
(source https://github.com/microsoft/msphpsql/blob/a8138e1de60eb6e97c7cc99410fff9c973e188ab/source/pdo_sqlsrv/pdo_dbh.cpp#L1336)

[philip]

In addition:

• The list appears incomplete, which is worth noting (subtly or otherwise)
• The list contains PDO::ATTR_DRIVER_NAME whereas the example code does not
• Example should gracefully handle the exceptions (see user comments for hints on how)
• Rephrase in a stronger way, I'm guessing no driver supports all attributes as opposed to how today the docs contain Note that some database/driver combinations may not support all of the database connection attributes.