Feat/convert mdbook/144

[mehtaishita]

Problem

Our static site generator (docz) isn't really meeting our needs currently.

144

Solution

Using mdBook as our static site generator to take advantage of improved functionality:

• Nested menus in the sidebar
• Multiple themes
• Better configuration opportunities
• Multiple third-party plugins

with @wilwade

Change summary:

This is Pull request 1 of 3. See comment for next steps

• [x] Updated dependencies in package.json
• [x] Removed docz and generated spec with mdBook
• [x] Configured styles to have a cleaner look
• [x] Add custom var for sidebar menu folding and collapsing nested menus
• [x] Added third-party plugin mdBook-linkcheck for checking broken links
• [x] Added github repo URL to the menu bar for more transparency
• [x] Replaced absolute URLs with relative ones
• [x] Used provided handlebars to add DSNP logo, and external link to the developer portal

Steps to Verify:

From root dir:

1. npm install clean
2. npm run build
3. Build process will run a link-check to check for broken links
4. npm run lint
5. npm run serve
6. The spec will automatically open in your web browser
7. Click around for internal and external links

Screenshots (optional):

[mehtaishita]

• [ ] Styling issues - ensure colors and highlights are more consistent
• [ ] The default theme when building/serving is not consistent
• [ ] The github edit link for index.md is broken - however the rest are working fine
• [ ] The developer portal link is not formatted consistently as the others
• [ ] Explore available third party plugins to also show headers in the sidebar toc