Convert architecture drawings/schemas to dark mode on docs

[jess-lowe]

For more consistent branding and a cohesive design, the architecture diagrams should be converted to dark mode in the docs.

Relevant pages with diagrams include:

• Main landing page
• Architecture page

[Kunal9027]

@jess-lowe you want to convert diagram images theme from white to black . can i work om this issue

i also want to join the community if there is any slack group . where i can show the images before making a PR

[jess-lowe]

Hey @Kunal9027, I'll assign this to you too.

The best way to get involved is to join the OpenSSF slack group and join the osv-scanner-scalibr channel. :)

Thanks for getting involved!