Feature- add examples for math functions

[singla-shivam]

There are logical functions like- add, subtract, mean etc. We need to add examples for these functions to be consumed by the site for "Try on playground"

[singla-shivam]

@kumar-praveen-k , @neelra8n we don't need to add console.assert("Example ran successful") statement at the end of the examples. Instead, we will show a notification/popup in the playground to indicate the script ran successfully in case of no assertion or other errors.

Ref- #68