Documentation/filesystems/xfs: Fix typo error

Fixed typo error in referring to the section's headline
Fixed to correct spelling of "mapping"

Signed-off-by: Alperen Aksu <[e-mail]>
Reviewed-by: Randy Dunlap <[e-mail]>
Signed-off-by: Jonathan Corbet <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

Documentation/filesystems/xfs/xfs-online-fsck-design.rst

···
 shutdown.
 
 Inspiration for the secondary metadata repair strategy was drawn from section
-2.4 of Srinivasan above, and sections 2 ("NSF: Inded Build Without Side-File")
+2.4 of Srinivasan above, and sections 2 ("NSF: Index Build Without Side-File")
 and 3.1.1 ("Duplicate Key Insert Problem") in C. Mohan, `"Algorithms for
 Creating Indexes for Very Large Tables Without Quiescing Updates"
 <https://dl.acm.org/doi/10.1145/130283.130337>`_, 1992.
···
    This will be discussed in more detail in subsequent sections.
 
 If the filesystem goes down in the middle of an operation, log recovery will
-find the most recent unfinished maping exchange log intent item and restart
+find the most recent unfinished mapping exchange log intent item and restart
 from there.
 This is how atomic file mapping exchanges guarantees that an outside observer
 will either see the old broken structure or the new one, and never a mismash of