btrfs-progs: doc: fix typo of some documents

Some typos are corrected.

Signed-off-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Documentation/btrfs-check.asciidoc

@@ -24,7 +24,7 @@ OPTIONS
 -------
 -s|--super <superblock>::
 use <superblock>th superblock copy, valid values are 0 up to 2 if the
-respective superblock offset is within the fileystem
+respective superblock offset is within the filesystem
 --repair::
 try to repair the filesystem
 --init-csum-tree::
@@ -32,7 +32,7 @@ create a new CRC tree and recalculate all checksums
 --init-extent-tree::
 create a new extent tree
 --check-data-csum::
-verify checkums of data blocks
+verify checksums of data blocks
 -p|--progress::
 indicate progress at various checking phases
 --qgroup-report::

Documentation/mkfs.btrfs.asciidoc

@@ -78,7 +78,7 @@ where the space is reserved for the other block group type, is not available for
 allocation and can lead to ENOSPC state.
 +
 The recommended size for the mixed mode is for filesystems less than 1GiB. The
-soft recommendation is to use it for filesystems smaller than 5GiB. Thie mixed
+soft recommendation is to use it for filesystems smaller than 5GiB. The mixed
 mode may lead to degraded performance on larger filesystems, but is otherwise
 usable, even on multiple devices.
 +