docs: filesystems: Fix a mundane typo

s/provisoned/provisioned/

Signed-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Link: https://lore.kernel.org/r/20210319015848.19515-1-unixbhaskar@gmail.com


Signed-off-by: Jonathan Corbet <corbet@lwn.net>