TE example with Pebble

**Is your feature request related to a problem? Please describe.**
The current templating example use Handlebars. We should update the tutorial to use Handlebars and Pebble.

**Describe the solution you'd like**
Process the page containing two snippets:
- with Handlebars syntax
- with Pebble syntax

Please note that we can simply replace TE syntax without data changes.

**Additional context**
- move the example assets from https://github.com/Knotx/knotx-fragments#supply-fragments

Locate the current Handlebars templating example and its tutorial assets in this repository, then review the referenced supply-fragments repository for the assets to move. The finished example should process one page containing both Handlebars and Pebble snippets without changing the data.

Written by the indexing model from the issue text.