docs: hugetlbpage.rst: fix a typo of hugepage size

should be kB instead of Kb

Signed-off-by: Hoi Pok Wu <wuhoipok@gmail.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Link: https://lore.kernel.org/r/20220922030645.9719-1-wuhoipok@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Author: qlyjsld

Documentation/admin-guide/mm/hugetlbpage.rst

@@ -65,7 +65,7 @@ HugePages_Surp
 	may be temporarily larger than the maximum number of surplus huge
 	pages when the system is under memory pressure.
 Hugepagesize
-	is the default hugepage size (in Kb).
+	is the default hugepage size (in kB).
 Hugetlb
         is the total amount of memory (in kB), consumed by huge
         pages of all sizes.