docs/help: rename defconfig/olddefconfig into

After commit 15f57d843296e244487ac0845a73247f9d6749b8, the defconfig target
has been renamed into savedefconfig, and olddefconfig into defconfig. However,
the help text and man page was not updated.

Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
[yann.morin.1998@free.fr: rename CONFIG -> DEFCONFIG]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Message-Id: <0c1dff89c9ee1672693f.1374042343@BEANTN0L019720>
Patchwork-Id: 259601

CT_EXPERIMENTAL=y

CT_LOCAL_TARBALLS_DIR="${HOME}/src"

CT_SAVE_TARBALLS=y

CT_LOG_EXTRA=y

CT_ARCH_LE=y

CT_ARCH_64=y

CT_ARCH_FLOAT_SW=y

CT_ARCH_mips=y

CT_TARGET_VENDOR="n32"

CT_KERNEL_linux=y

CT_KERNEL_V_2_6_31=y

CT_BINUTILS_V_2_19_1a=y

CT_CC_V_4_3_2=y

CT_CC_LANG_CXX=y

CT_LIBC_uClibc=y

CT_LIBC_UCLIBC_V_0_9_30_1=y

CT_LIBC_UCLIBC_CONFIG_FILE="${CT_LIB_DIR}/samples/${CT_TARGET}/${CT_LIBC}-${CT_LIBC_VERSION}.config"

CT_GMP_V_4_3_2=y

CT_MPFR_V_2_4_2=y