t1300: fix config file syntax error descriptions

Three tests in t1300-config.sh check that "git config --get" barfs when the config file contains various syntax errors: key=value pair without equals sign, broken section line, and broken value string. The sample config files include a comment describing the kind of broken syntax. This description seems to have been copy-pasted from the "broken section line" sample to the other two samples. Fix descriptions of broken config file syntax in samples used in t1300-config.sh. Signed-off-by: Andrei Rybak <rybak.a.v@gmail.com> Reviewed-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>