Add search text box to the web page

[suthagar23]

Add a search text box to the web page between the top header and table with a placeholder as "Search environment keys..."

Need this to be fixed for #9

[wcorderolara]

If you want, you can assign this to me, will be a pleasure helping to you

[dandelionsam]

I can help too, if you want :)

[suthagar23]

Assigned to @wcorderolara as per the first request, if he can't manage this I will assign this to @dandelionsam . Thanks