Added external repos in Examples

[TugdualKerjan]

Based on the discussion on #936 - I seperated the notebooks from the external repos, and added some projects from the awesome list mentionned - is this how you saw things ?

[patrick-kidger]

Ah, awesome!
So my guess is that having the list of these projects live in the sidebar is going to get quite unwieldy as we add to this list. (And there's quite a few other external projects I know of that I'd like to add here!)

For that reason I'm thinking it might be easier to put them on a single page, and then have that page somewhere prominent in the sidebar. Maybe something like:

# mkdocs.yml

nav:
    ...
    - Examples:
        - Introductory: 
            ...
        - Advanced:
            ...
        - Features:
            ...
        - Awesome list: 'examples/awesome-list.md'

# awesome-list.md

Details here!

WDYT?

[TugdualKerjan]

definetly agree - changes made with a short description to make it a little bit clearer what each project points to etc !

tell me if anything needs changing on my part 👍

[patrick-kidger]

LGTM! Merged :) I'm very happy to have this in (and I'm about to add a few more projects to it :) )

[TugdualKera]

Thanks !!! This is my first PR ever :) Won't be my last !