Update SUMMARY.md

SUMMARY.md

@@ -13,6 +13,7 @@
     * [Kernel entry point](Initialization/linux-initialization-4.md)
     * [Continue architecture-specific boot-time initializations](Initialization/linux-initialization-5.md)
     * [Architecture-specific initializations, again...](Initialization/linux-initialization-6.md)
+    * [End of the architecture-specific initializations, almost...]()
 * [Memory management](mm/README.md)
     * [Memblock](mm/linux-mm-1.md)
     * [Fixmaps and ioremap](mm/linux-mm-2.md)