Update SUMMARY.md

SUMMARY.md

@@ -9,6 +9,7 @@
 * [Initialization](Initialization/README.md)
     * [First steps in the kernel](Initialization/linux-initialization-1.md)
     * [Early interrupts handler](Initialization/linux-initialization-2.md)
+    * [Kernel entry point]()
 * [Theory](Theory/README.md)
     * [Paging](Theory/Paging.md)
     * [Elf64](Theory/ELF.md)