Typo

Fix one small typo.

linux-bootstrap-1.md

@@ -456,7 +456,7 @@ Jump to main
 That's all, we have stack, bss and now we can jump to `main` C function:
 
 ```assembly
-	calll main
+	call main
 ```
 
 which is in [arch/x86/boot/main.c](https://github.com/torvalds/linux/blob/master/arch/x86/boot/main.c). What will be there? We will see it in the next part.