docs: update stories featuring bootstrap

[ahasall]

Bootstrap 4 has been released.
npm install bootstrap --save installs Bootstrap 4 instead of Bootstrap 3.
To install Boostrap 3, we should do npm install bootsrap@3

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[ahasall]

I signed it!

[googlebot]

CLAs look good, thanks!

[markgoho]

Do we typically add instructions for adding old packages to projects? I'd suggest we remove the v.3 installation notes altogether.

[ahasall]

Yes. You are right. I updated the PR.

[rafaelss95]

It's not something you added, but can we add that neither jquery nor popper.js are needed if you pretend to use only CSS? With the current docs people tend to feel that they have to install them obligatory.

[ahasall]

I totally agree with you. I will update my PR accordingly.

[ahasall]

I updated the PR. Tell me what you think about the changes.

[ahasall]

@markgoho or @rafaelss95,
Is there any action I can take to improve this PR so that it can be merged ?
Thanks

[filipesilva]

Heya, this pr is superseded by #10541.

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