Simple introductory video

It seems like novice Embereños find it increasingly hard to get started with ember-light-table. Most already struggle with passing a `table` to their `{{light-table}}` component invocation in the template and [get this error](https://github.com/offirgolan/ember-light-table/blob/0edf5d0adace49a63de1eb1cbc52ada0cf4188ed/addon/components/light-table.js#L236-L239):

```
[ember-light-table] table must be an instance of Table
```

The [live demo page and cookbok](https://offirgolan.github.io/ember-light-table/) are great for the more experienced developers, but are way too complicated for beginners. Many don't seem to understand the `simple-table` mixin.

We're happy to assist users in our #e-light-table slack channel, but having to answer the same questions all over again is needlessly time-consuming and frustrating, for supporters and users alike.
One user mentioned that there was a vimeo video showcasing ember-light-table, but it was apparently removed.

tbh I didn't even know about that video, but I think it's an awesome idea. Someone (?) should create a short introductory video, that shows how to create a *very simple* ELT component. No mixins, no ember-concurrency, no special stuff. A second video might show these advanced concepts and maybe transform this basic table into the `simple-table` example from the demo page.

---

Exemplary issues:

https://github.com/offirgolan/ember-light-table/issues/21 https://github.com/offirgolan/ember-light-table/issues/407