docs: update swapext -> exchmaps language

Start reworking the atomic swapext design documentation to refer to its
new file contents/mapping exchange name.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Darrick J. Wong 2024-04-15 14:54:25 -07:00
commit f783529bee