Add instructions for orgs

Organizations don't have models enabled by default, but they're needed
for this to work

Author: slifty

README.md

@@ -102,6 +102,36 @@ You can override the model with any model supported by the chosen provider.
    - Things to watch for
 4. Posts (or updates) the instructions as a PR comment, identified by a hidden HTML marker
 
+## Troubleshooting
+
+### GitHub Models returns 403 Forbidden
+
+If you see a 403 error when using the `github-models` provider, GitHub Models may be disabled at the organization level. GitHub Models uses a hierarchical access control system:
+
+1. **Enterprise level** — An enterprise owner must enable GitHub Models for the enterprise (if your organization is part of an enterprise)
+2. **Organization level** — An organization owner must enable GitHub Models for the organization
+3. **Workflow level** — Your workflow must declare `permissions: models: read` (already in the example above)
+
+**To enable GitHub Models for your organization:**
+
+An organization owner needs to:
+
+1. Navigate to your organization's **Settings**
+2. Go to **Code, planning, and automation** → **Models** → **Development**
+3. Enable GitHub Models for the organization
+
+**Alternative workaround:**
+
+If you cannot enable GitHub Models at the organization level, switch to the Anthropic provider:
+
+```yaml
+- uses: BadIdeaFactory/qa-instructions-action@v1
+  with:
+    github-token: ${{ secrets.GITHUB_TOKEN }}
+    provider: anthropic
+    anthropic-api-key: ${{ secrets.ANTHROPIC_API_KEY }}
+```
+
 ## Development
 
 ### Setup