Document how to fix 'Reasource not Available by Integration'

[GabLeRoux]

Related issue: game-ci/unity-test-runner#249

Reasource not Available by Integration

This message is related to the following StackOverflow:
https://stackoverflow.com/questions/70435286/resource-not-accessible-by-integration-on-github-post-repos-owner-repo-ac

This happens because the pipeline doesn't have the right to publish the report for the tests.

Option 1: Go in project's settings > Workflow Permissions section and give actions Read and Write permissions.
Option 2: explicitly add the required permissions to the job using this action, e.g.:

jobs:
  test:
    permissions:
      checks: write
...
    steps:
      - name: Run Tests
        uses: game-ci/unity-test-runner@v4

source: game-ci/unity-test-runner#249 (comment)

1. Identify all example snippets in our docs that would benefit from the permissions. Can be done by searching for "game-ci/unity-test-runner" in the code (yaml snippets).
2. Update the examples with the permissions check
3. Document the error, the fix and the permission check somewhere.

The last thing I would like to validate: if we have the permissions checks in the yaml, I suppose we still have to give actions Read and Write permissions, is that right?

[asbjornu]

A note on this: If permissions: is added, all default permissions for other actions in the job are reset and will have to be explicitly added back. As mentioned in actions/checkout#254, actions/checkout will stop working since it needs contents: read permissions, for instance.