feat(): added dropdown for nestjs versions

[Tony133]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/docs.nestjs.com/blob/master/CONTRIBUTING.md

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[x] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] Docs
[x] Other... Please describe:

What is the current behavior?

Issue Number: "takes its cue from this problem" #64

What is the new behavior?

N/A

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

This PR, added to the dropdown for nestjs versions, could be a useful addition to the documentation, to navigate between the old and new versions of NestJS, I am attaching here two screenshots both when the menu is open and when it is closed.

Also in the future as there are more versions of NestJS it could be useful.

dropdown open:

dropdown close:

a small clip:

draft-version-nest-menu.mov

[jmcdo29]

I'll admit, this looks pretty cool. I personally like that it opens a new tab for the version as the version is just a snapshot of the last push for that version.

Definitely a blast from the past to see v4 and v5.

[kkoomen]

Good addition. I think we should make the label include the version or do something equivalent like laravel: https://laravel.com/docs/8.x

We can do : Version: ${version} so that a user always can quickly confirm the current documentation version he/she is looking at.

[Tony133]

Hi all, I have updated the dropdown version by adding the latest version now it is dynamic based on the npm publication (see screenshot), let me know what you think.

[micalevisk]

Suggested change

	<a href="https://docs.nestjs.com/v8/" target="_blank">8.x</a>
	<a href="https://docs.nestjs.com/v7/" target="_blank">7.x</a>
	<a href="https://docs.nestjs.com/v6/" target="_blank">6.x</a>
	<a href="https://docs.nestjs.com/v5/" target="_blank">5.x</a>
	<a href="https://docs.nestjs.com/v4/" target="_blank">4.x</a>
	<a href="https://docs.nestjs.com/v8/" target="_self">8.x</a>
	<a href="https://docs.nestjs.com/v7/" target="_self">7.x</a>
	<a href="https://docs.nestjs.com/v6/" target="_self">6.x</a>
	<a href="https://docs.nestjs.com/v5/" target="_self">5.x</a>
	<a href="https://docs.nestjs.com/v4/" target="_self">4.x</a>

wouldn't this behavior be better? I mean, if one want to see the docs of another version, they problably don't care about the current one

[dijonkitchen]

This would be good for reviewing documentation on migrating older versions.