Documentation: filesystems: btrfs: Fixed typos and whitespace

I am a high school student trying to become familiar with
Linux kernel development. The btrfs documentation in
Documentation/filesystems had a few typos and errors in
whitespace. This patch corrects both of these.

Signed-off-by: Daniel Grimshaw <grimshaw@linux.vnet.ibm.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/filesystems/btrfs.txt

@@ -135,7 +135,7 @@ Options with (*) are default options and will not show in the mount options.
 	a metadata B-tree leaf.  The value is specified in bytes, optionally
 	with a K, M, or G suffix, case insensitive.  In practice, this value
 	is limited by the root sector size, with some space unavailable due
-	to leaf headers.  For a 4k sectorsize, max inline data is ~3900 bytes.
+	to leaf headers.  For a 4k sector size, max inline data is ~3900 bytes.
 
   metadata_ratio=<value>
 	Specify that 1 metadata chunk should be allocated after every <value>
@@ -194,7 +194,7 @@ Options with (*) are default options and will not show in the mount options.
   ssd_spread
 	Options to control ssd allocation schemes.  By default, BTRFS will
 	enable or disable ssd allocation heuristics depending on whether a
-	rotational or nonrotational disk is in use.  The ssd and nossd options
+	rotational or non-rotational disk is in use.  The ssd and nossd options
 	can override this autodetection.
 
 	The ssd_spread mount option attempts to allocate into big chunks