Third-party search results should distinguish between v1 & v2

[mrienstra]

When using Google Search to find something Yarn-related, I often end up on classic.yarnpkg.com (Yarn 1 docs site). I find it difficult to predict which docs site (1 or 2) I'll get to by looking at Google Search results.

An example:

A search for yarn upgrade-interactive:

The first result points to https://yarnpkg.com/lang/en/docs/cli/upgrade-interactive/, which 301 (Moved Permanently) redirects to https://classic.yarnpkg.com/en/docs/cli/upgrade-interactive/ (Yarn 1 docs)

The second result (below the "People also ask" section) points to https://yarnpkg.com/cli/upgrade-interactive/, which does not redirect (Yarn 2 docs)

The ranking might be what's right for most people -- perhaps there is still more interest in Yarn 1 than Yarn 2? Judging by https://www.npmjs.com/package/yarn vs. https://www.npmjs.com/package/@yarnpkg/core that's definitely the case, but not sure if that's apples-to-apples.

The challenge is in telling them apart at a glance. Some ideas:

1. Migrate* Yarn 1 fully to the classic.yarnpkg.com subdomain. Downside: this could hurt SEO.
2. Change the Yarn 1 <title>s to include "1" or "classic".
3. Change the Yarn 2 <title>s to include "2" or "berry".

*: By which I mean tell Google to finally let go of the old URLs and start showing the news ones. It's been a minute since I've done this, but happy to dig into it if that would be useful. More info here.

... Oh yeah, here's why Google isn't showing the classic.yarnpkg.com subdomain: page HTML includes:

<link rel="canonical" href="https://yarnpkg.com/lang/en/docs/cli/upgrade-interactive/">

PS: I'm aware that changing the search query to yarn 2 upgrade-interactive (or "yarn 2" upgrade-interactive which I often do) helps (first result is Yarn 2 docs, and summary includes "... Important: This documentation covers Yarn 2. ..."), but I still feel this is worth improving. I'm also aware that Google is not the only game in town, it just happens to be the most commonly used.

Bing & DuckDuckGo both show the classic.yarnpkg.com subdomain in search results for Yarn 1 docs, which is definitely an improvement over Google:
https://www.bing.com/search?q=yarn+upgrade-interactive
https://duckduckgo.com/?q=yarn+upgrade-interactive

[mrienstra]

Focusing on "1" above first (yarnpkg.com --> classic.yarnpkg.com), PR here: yarnpkg/website#1133

Update: merged!