Version dropdown is not rendered when there is only next and some other version.

[maksnester]

🐛 Bug Report

Version dropdown has no dropdown.

Have you read the Contributing Guidelines on issues?

yes

To Reproduce

1. Have only one /docs folder without versions
2. Run yarn run docusaurus docs:version 1.x
3. Add versions dropdown to the navbar

     {
          type: 'docsVersionDropdown',
          position: 'left',
        },

Expected behavior

Dropdown with 2 versions is visible in the navbar.

Actual Behavior

Only one 1.x version is visible.

Your Environment

2.0.0-alpha.64

Reproducible Demo

Sorry, maybe later. But the root of the problem is in theme-classic that has DocsVersionDropdownNavbar component where that code exists:

 // We don't want to render a version dropdown with 0 or 1 item
    // If we build the site with a single docs version (onlyIncludeVersions: ['1.0.0'])
    // We'd rather render a buttonb instead of a dropdown
    if (versions.length <= 2) {
      return undefined;
    }

The next version is a hidden version and doesn't count and it's not mentioned in versions.json.

[lex111]

Already fixed in #3472 but thank you for the report.