docs/website: Change highlight.js Theme

[NightOwl888]

On both our main website and the API docs site, we should change the theme of the code highlighter. There are 2 issues we hope to solve:

• Make the code look more like it does in Visual Studio.
• Make the inline code blocks more visible. Currently, they look like disabled text.

It really strains your eyes to look at the current theme too long.

There is a blog post that specifically outlines the steps how to change the theme with DocFx:

https://www.cazzulino.com/customize-docfx.html

One theme I thought would be okay was the VS theme here, but the one from the blog post (which I haven't previewed) might be closer to what we are looking for. But as long as the text looks less faded than it does now, it would be an improvement.

Note that the themes of DocFx are already exported to the /websites/apidocs/Templates/DefaultTemplateNoAssets folder so they can be copied over to the "live" folders and modified easily.

[krylowicz]

I'll take it.

[NightOwl888]

Great, and thanks for volunteering. I have assigned the issue to you.

[NightOwl888]

BTW - the info about how to do a local build of the docs and website is here:

https://lucenenet.apache.org/contributing/documentation.html

[rclabo]

@krylowicz How's it coming. If you have questions fee free to post them here with this issue. Thanks again for volunteering for this one. You are appreciated!