Create README and Index for DCE samples

[Felix-Dynamsoft]

We'll need to create a Table of Contents which would be included in the README and index.html for the samples in DCE.
This way, we'll be able to link how to customize the UI through DBR or other libraries.

For reference, this is DBR's sample lists: https://github.com/Dynamsoft/barcode-reader-javascript-samples

[Tom-Dynamsoft]

@a362758199 Please help create something for this repo like the README for DBR JS Samples