Added sitemap.xml for SEO

[jookwang-park]

How do you think about creating a sitemap.xml file for the Google Search Engine?

I'm using it already, check it out. Here is a result of generating a sitemap.xml

[samarsault]

Nice addition. I think an option to toggle the sitemap in _config.yml would be a useful addition.

[jookwang-park]

Thank you for your comment. I have the following questions.

1. How do you think about to add a sitemap option in _config.yml globally or in plainwhite section?
2. If a sitemap option is set to false, what sitemap.xml content will be rendered?

[samarsault]

1. In the plainwhite section
2. You could do something like this in the sitemap.xml file:

{%-if site.plainwhite.sitemap -%}
    // generated content
{%- endif -%}

[jookwang-park]

I added the sitemap option. The default 'sitemap' option value is true. If necessary, you can change the default value! And, Maybe the sitemap option should be added to the README file?

Best regards.

[samarsault]

Yeah, add it to the README file and squash your commits into one so that I could proceed with the merge.

[jookwang-park]

I write a sitemap manual to the README and squash my commits. Check it out please.

[samarsault]

Great!