Add a Theme toggle button

[indrasuthar07]

Check List

• [x] I have already read README.
• [x] I have already searched existing issues.
• [x] I have already searched existing pull requrests.

Feature Request

The website is in light white theme and so add a theme toggle button in navbar so it's easy for eyes to read documentation. add a theme toggle button like in github , we can change theme dark to bright and bright to dark

Additional context

No response