X86: Add a couple comments to the bios SConscript

src/arch/x86/bios/SConscript

@@ -59,7 +59,10 @@ Import('*')
 
 if env['TARGET_ISA'] == 'x86':
     if env['FULL_SYSTEM']:
+        # The table generated by the bootloader using the BIOS and passed to
+        # the operating system which maps out physical memory.
         SimObject('E820.py')
         Source('e820.cc')
 
+        # The DMI tables.
 	Source('smbios.cc')