Uniformize examples readme and quickstart [ready for reviews]

[bcm-at-zama]

Mainly, this PR is to unify examples in README and in quick_start.md, as requested by @yuxizama.

closes zama-ai/concrete-internal#603

By the way, I used the opportunity to update a bit the example

• with no more hardcoded pairs (clearer inputset, clearer samples for execution)
• with an assert of the correct execution

I find this example easier to be reused for users (eg, me, each time, I apply this very same change). Is it ok with you?

[bcm-at-zama]

@BourgerieQuentin , @umut-sahin , you'll tell me if you're fine with these changes. And then, we'll have to handle the conflicts in the other PR by @yuxizama (#700)

[bcm-at-zama]

Let me fix the build.

[bcm-at-zama]

Note that we could squash the commits, I just made them separate for you to have a look to my changes in the example itself.

[bcm-at-zama]

And we can make it reviewed by an English native speaker before pushing.

[bcm-at-zama]

Thanks @BourgerieQuentin for your feedback. Do you want to take the lead now on this PR, and change what you want? What we need at least is to uniformize the README and QuickStart. For the rest, you can do what you want. Just maybe wait that #700 is merged before merging this one.

[BourgerieQuentin]

any feedback @bcm-at-zama @yuxizama ?

[bcm-at-zama]

Thx, let me have a look

[bcm-at-zama]

I really dislike the fact that it has been over simplified:

• for newbies: it's not clear to me that they shouldn't hardcode their inputset; it's not clear that they should have long inputset
• for developers: I use the README to have a template I can change; each time I'll have to re-add what I did previously in this PR, which is having random and with a chosen-bit width inputs.

But I guess we have to converge so I'll accept.

[bcm-at-zama]

Let me make this build green.

[bcm-at-zama]

Rebased and fixed lint

[bcm-at-zama]

Build is green

[bcm-at-zama]

Rebasing

[BourgerieQuentin]

pushed on release/v2.6.0