The aria2c command tries to load config from
${XDG_CONFIG_HOME:-${HOME}/.config}/aria2/aria2.conf by default,
which may result unexpected behavior.
As a replacement, people can use environment variable ARIA2C_OPTIONS
to custom arguments passed to aria2c like curl and wget below.
Including --conf-path=/path/to/config.conf in ARIA2C_OPTIONS can
also set a custom config file path easily if needed.
Signed-off-by: Zhang Hua <zhanghuadedn@gmail.com>
