README.scrapyard: add entries for dead AVR32 boards

Some AVR32 boards were dropped by the following commits:
 9eb45aabe078 (avr32: delete non generic board favr-32-ezkit)
 e36930764471 (avr32: delete non generic board hammerhead)
 c62d2f8fc5c6 (avr32: delete non generic board mimc200)
 e5354b8a9e2a (avr32: delete non generic board's atstk100{3, 4, 6})

Acked-by: Andreas Bießmann <andreas.devel@googlemail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

doc/README.scrapyard

@@ -12,6 +12,12 @@ The list should be sorted in reverse chronological order.
 
 Board            Arch        CPU            Commit      Removed     Last known maintainer/contact
 =================================================================================================
+atstk1003        avr32       -              e5354b8a    2015-06-10  Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
+atstk1004        avr32       -              e5354b8a    2015-06-10  Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
+atstk1006        avr32       -              e5354b8a    2015-06-10  Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
+mimc200          avr32       -              c62d2f8f    2015-06-10  Mark Jackson <mpfj@mimc.co.uk>
+hammerhead       avr32       -              e3693076    2015-06-10  Alex Raimondi <alex.raimondi@miromico.ch>
+favr-32-ezkit    avr32       -              9eb45aab    2015-06-10  Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
 afeb9260         arm         arm926ejs      f6b42c14    2015-05-13  Sergey Lapin <slapin@ossfans.org>
 tny_a9260        arm         arm926ejs      f6b42c14    2015-05-13  Albin Tonnerre <albin.tonnerre@free-electrons.com>
 sbc35_a9g20      arm         arm926ejs      f6b42c14    2015-05-13  Albin Tonnerre <albin.tonnerre@free-electrons.com>