feat: improve readability of docs

[kenyiu]

While adding openAPI documentation, found pretty annoying when navigating the docs because of the big banner and logo. Every time after navigating, i will need to scroll down half of my screen since the top half is occupied by the banner and the logo when the user first loaded into docs.

So following changes are recommended.

• Removed the large banner image from the home page
• Resized the DrandLogo to a smaller size to prevent it from occupying the whole screen

Before:

After: