add index.html to samples

[AlbyIanna]

I've added index.html files to the samples root folders, and used HtmlWebpackPlugin to add them to the dist folder and add the <script> tag at the end of the body when you run npm run build.

I don't like the idea to copy the same index.html file in each sample, but I guess it's the only way if the aim is to keep them separated.

This should solve #9.

[AlbyIanna]

@adaddeo since you decided to put index.html files directly inside the dist folder (#9), I think we can close this PR.