docs: The url to the yarn corepack documentation is not found (invalid url) when corepack is enabled for the repo, but not the action.

[jpbnetley]

Originally I filed this bug under setup node: actions/setup-node#1206 (comment)
But it was pointed out that the message was a yarn specific error message.

In summary:
The project was migrated to yarn berry (in my case [email protected])
I have a Github action setup that tries to build the project when core pack is not yet enabled.

The following error is presented when the Github action tries to run the setup node.

Run actions/setup-node@v4
Found in cache @ /opt/hostedtoolcache/node/20.18.1/x64
Environment details
/usr/local/bin/yarn --version
1.22.22
/usr/local/bin/yarn cache dir
error This project's package.json defines "packageManager": "[email protected]". However the current global version of Yarn is 1.22.22.

Presence of the "packageManager" field indicates that the project is meant to be used with Corepack, a tool included by default with all official Node.js distributions starting from [16](https://github.com/AlbatrosEng/a9-cwi-client/actions/runs/12948571237/job/36117499630?pr=172#step:3:18).9 and 14.19.
Corepack must currently be enabled by running corepack enable in your terminal. For more information, check out https://yarnpkg.com/corepack.
Error: error This project's package.json defines "packageManager": "[email protected]". However the current global version of Yarn is 1.22.22.

Presence of the "packageManager" field indicates that the project is meant to be used with Corepack, a tool included by default with all official Node.js distributions starting from 16.9 and 14.[19](https://github.com/AlbatrosEng/a9-cwi-client/actions/runs/12948571237/job/36117499630?pr=172#step:3:21).
Corepack must currently be enabled by running corepack enable in your terminal. For more information, check out https://yarnpkg.com/corepack.

I noticed that the link provided in the error is not found, because it includes a full stop.
The link should be https://yarnpkg.com/corepack and not https://yarnpkg.com/corepack.

To reproduce

Repro steps:
I used the migration docs here to upgrade from yarn 1 to the new version.
But I think it can be re-produced with the following:

• create a repo with yarn.
• Then enable corepack for yarn corepack enable
• Update yarn to the latest with yarn set version berry
• And then let the github action run
  The action I use as an example:

  name: Code Validation

on:
  workflow_call:

env:
  node_version: 20

jobs:
  tests:
    name: Test
    runs-on: ubuntu-latest
    
    steps:
    - uses: actions/checkout@v4

    - name: Use Node.js ${{ env.node_version }}
      uses: actions/setup-node@v4
      with:
        node-version: ${{ env.node_version }}
        cache: 'yarn'

    - uses: actions/cache@v4
      id: npm-cache
      with:
        path: node_modules
        key: ${{ runner.os }}-${{ env.node_version }}-node-${{ hashFiles('**/yarn.lock') }}
        restore-keys: ${{ runner.os }}-${{ env.node_version }}-node-
      
    - name: Install    
      if: steps.npm-cache.outputs.cache-hit != 'true'  
      run: yarn