Update README.md

mm/README.md

@@ -5,3 +5,4 @@ couple of posts which describe different parts of the linux memory management fr
 
 * [Memblock](https://github.com/0xAX/linux-insides/blob/master/mm/linux-mm-1.md) - describes early `memblock` allocator.
 * [Fix-Mapped Addresses and ioremap](https://github.com/0xAX/linux-insides/blob/master/mm/linux-mm-2.md) - describes `fix-mapped` addresses and early `ioremap`.
+* [kmemcheck](https://github.com/0xAX/linux-insides/blob/master/mm/mm-3.md) - third part describes `kmemcheck` tool.