fixes #11

[trangntt-016]

No description provided.

[trangntt-016]

Hi @dbelokon , here are the features I've just added to your code, pls check it.
[x] The -c or --config flags accept a file path to a JSON config file.
[x] If the file is missing, or can't be parsed as JSON, exit with an appropriate error message.
[x] If the -c or --config option is provided, ignore all other options (i.e., a config file overrides other options on the command line).
[x] The program should ignore any options in the config file it doesn't recognize. For example, if the SSG doesn't support stylesheets, ignore a stylesheet property.
[x] If the config file is missing any options, assume the usual defaults. For example, use dist/ as the output directory if it isn't specified.

[dbelokon]

Wow!! Looks nice! thank you for your contribution! @trangntt-016

[trangntt-016]

My pleasure @dbelokon 😄