chore: create `docs` folder under the root folder

[inigomarquinez]

The objective of this PR is to have a docs folder under the root folder for all the files related to documentation.

Before it was under the /tools folder, which didn't make too much sense.

Apart from that, the packages-in-scope.md file has also been moved from /tools/scope to this new /docs folder.

[UlisesGascon]

Additionally we will need to update:

• https://github.com/expressjs/express/blob/master/Security.md?plain=1#L51
• https://github.com/expressjs/security-wg/blob/main/README.md?plain=1#L10

As the reference have changed :)

[inigomarquinez]

Additionally we will need to update:

• https://github.com/expressjs/express/blob/master/Security.md?plain=1#L51
• https://github.com/expressjs/security-wg/blob/main/README.md?plain=1#L10

As the reference have changed :)

@UlisesGascon do I create the PRs or do I wait until this PR is merged?

[UlisesGascon]

do I create the PRs or do I wait until this PR is merged?

Feel free to create them, so we will merge queue them

[inigomarquinez]

@UlisesGascon

I've already created a PR to update the reference to the Thread Model in the express documentation and I've modified this same PR to fix the location of the packages-in-scope.md file.