Install Unreleased Symfony Version uses 2.7 as example

[alexislefebvre]

This page shows how to install Symfony 2.7. So the example is outdated.

Should it be changed to the next LTS 3.4 or major release 4.0 instead? We may show as an exemple 3.3 today but the page will need to be updated after every release, every 6 months.

The page may also be improved by adding a link to the roadmap or releases so that users know what unstable versions are available.

[wouterj]

I think we may even delete the article, https://symfony.com/doc/current/setup.html#basing-your-project-on-a-specific-symfony-version shows how to install unstable versions.

[alexislefebvre]

Thanks @wouterj. Should I open a PR now or wait for more comments on this issue?

[HeahDude]

It is not outdated since 2.7 is still maintained. Doing so will install the master commit of this branch before next patch release instead of the current stable patch tagged in 2.7.

[wouterj]

Thinking about this a bit more, I think we should keep the article, but update some things:

• Reorder the sections, first do "Upgrading your Project to an Unstable Symfony Version" and then "Creating a New Project Based on an Unstable Symfony Version". Updating a project to test an RC release is more common than creating a new project to test it.
• Replace composer create-project with symfony new ... unstable install things (and especially the beta/RC commands, which can be usefull)
• Update both sections to focus more on installing RC and beta releases and less on installing the dev version.
• (Maybe updating the "Upgrading your Project to an Unstable Symfony Version" by installing a completely unthinking dev version, e.g. "Assume 2.94 hasn't been released yet")

If you can do the changes in a PR (or maybe just some of these), it would be very awesome! :)

[HeahDude]

Let's wait for Flex before doing to much change on this part :).

[alexislefebvre]

Now that Flex has been released, what should be done about the page mentioned in this PR?

[alexislefebvre]

This has been fixed in #8625.