t1300: fix config file syntax error descriptions

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>