Document following removals:

misc/bsdiff||2009-12-24|Incorporated into base system long ago
security/freebsd-update||2009-12-24|Incorporated into base system long ago
sysutils/est||2009-12-24|Incorporated into base system long ago
sysutils/estctrl||2009-12-24|Incorporated into base system long ago
sysutils/freebsd-sha1||2009-12-24|Incorporated into base system long ago
sysutils/freebsd-sha256||2009-12-24|Incorporated into base system long ago