Documentation: PCI: fix typo in pci.rst

Fix typo: "follow" -> "following" in pci.rst

Signed-off-by: Abdul Rahim <abdul.rahim@myyahoo.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <20240906205656.8261-1-abdul.rahim@myyahoo.com>