config: document array-capable variables

Update help entries for thos variables that accept multiple
arguments with spaces (aka. array-capable variables).

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

reporter_name="unknown"

reporter_url="http://iphonelinux.org/index.php/Glibc_toolchain_using_crosstool-NG"

reporter_comment="An (experimental) toolchain targeting the Apple's iPhone."