Update packedGit config option documentation.

Corrected minor typos and documented the new k/m/g suffix for
core.packedGitWindowSize and core.packedGitLimit.

[jc: with a minor markup fix.]

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/config.txt

@@ -123,20 +123,24 @@ core.packedGitWindowSize::
 	single mapping operation.  Larger window sizes may allow
 	your system to process a smaller number of large pack files
 	more quickly.  Smaller window sizes will negatively affect
-	performance due to increased calls to the opreating system's
+	performance due to increased calls to the operating system's
 	memory manager, but may improve performance when accessing
 	a large number of large pack files.  Default is 32 MiB,
 	which should be reasonable for all users/operating systems.
 	You probably do not need to adjust this value.
++
+Common unit suffixes of 'k', 'm', or 'g' are supported.
 
 core.packedGitLimit::
 	Maximum number of bytes to map simultaneously into memory
 	from pack files.  If Git needs to access more than this many
 	bytes at once to complete an operation it will unmap existing
 	regions to reclaim virtual address space within the process.
 	Default is 256 MiB, which should be reasonable for all
-	users/operating systems, except on largest Git projects.
+	users/operating systems, except on the largest projects.
 	You probably do not need to adjust this value.
++
+Common unit suffixes of 'k', 'm', or 'g' are supported.
 
 alias.*::
 	Command aliases for the gitlink:git[1] command wrapper - e.g.