Use the official Vale action available at https://github.com/errata-ai/vale-action

Automatically lint all modified text files in your GitHub pull requests. This GitHub action uses Vale to lint prose.

The github-action-vale-lint checks all modified text (including markup) files and reports failure on error.

You must have Vale configuration file .vale.ini in your repository.

1. Create a new file in your repository .github/workflows/action.yml.

   touch .github/workflows/pull_request.yml

2. Copy-paste the folloing workflow in your pull_request.yml file:

   name: Lint PRs with Vale
   on: pull_request
   jobs:
     vale-lint-PR:
       runs-on: ubuntu-latest
       steps:
       - uses: actions/checkout@master
         with:
           fetch-depth: 1
       - uses: gaurav-nelson/github-action-vale-lint@v0.1.0
         env:
           GH_COMMENT_TOKEN: ${{ secrets.GH_COMMENT_TOKEN }}

3. Or, if you want to lint all files (or files in a specific folder) and not just modified files, use the following workflow in your pull_request.yml file:

   name: Lint PRs with Vale
   on: pull_request
   jobs:
     vale-lint-PR:
       runs-on: ubuntu-latest
       steps:
       - uses: actions/checkout@master
         with:
           fetch-depth: 1
       - uses: gaurav-nelson/github-action-vale-lint@v0.1.0
         with:
           lint-all-files: 'yes' 
           dir-to-lint: 'directory/path/to/lint'
         env:
           GH_COMMENT_TOKEN: ${{ secrets.GH_COMMENT_TOKEN }}

If you want to show errors as comments on the pull request, in your repository:

1. Go to Settings > Secrets, and slect Add a new secret.
2. Enter GH_COMMENT_TOKEN for Name, and enter your secret token as Value.
3. Select Add secret.