Add darkmode button to the top

[Mohith234]

• The dark mode button is placed in the footer of the website.
• It would enhance the user experience if it is present at the top in the Navbar

[rohitmondal03]

Hello @Mohith234, I really want to work on this issue. Can you please assign me this issue ?

[alexdanilowicz]

Thanks for opening @Mohith234 and for jumping in @rohitmondal03, but the marketing site is actually a separate repo. So, I am closing this issue.