refactor: restructure documentation into organized docs directory (#383)

- Move FAQ.md to docs/faq.md
- Create structured documentation files:
  - setup.md: Manual setup and custom GitHub app instructions
  - usage.md: Basic usage and workflow configuration
  - custom-automations.md: Automation examples
  - configuration.md: MCP servers and advanced settings
  - experimental.md: Execution modes and network restrictions
  - cloud-providers.md: AWS Bedrock and Google Vertex setup
  - capabilities-and-limitations.md: Features and constraints
  - security.md: Security information
- Condense README.md to overview with links to detailed docs
- Keep CONTRIBUTING.md, SECURITY.md, CODE_OF_CONDUCT.md at top level

docs/cloud-providers.md

@@ -0,0 +1,95 @@
+# Cloud Providers
+
+You can authenticate with Claude using any of these three methods:
+
+1. Direct Anthropic API (default)
+2. Amazon Bedrock with OIDC authentication
+3. Google Vertex AI with OIDC authentication
+
+For detailed setup instructions for AWS Bedrock and Google Vertex AI, see the [official documentation](https://docs.anthropic.com/en/docs/claude-code/github-actions#using-with-aws-bedrock-%26-google-vertex-ai).
+
+**Note**:
+
+- Bedrock and Vertex use OIDC authentication exclusively
+- AWS Bedrock automatically uses cross-region inference profiles for certain models
+- For cross-region inference profile models, you need to request and be granted access to the Claude models in all regions that the inference profile uses
+
+## Model Configuration
+
+Use provider-specific model names based on your chosen provider:
+
+```yaml
+# For direct Anthropic API (default)
+- uses: anthropics/claude-code-action@beta
+  with:
+    anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}
+    # ... other inputs
+
+# For Amazon Bedrock with OIDC
+- uses: anthropics/claude-code-action@beta
+  with:
+    model: "anthropic.claude-3-7-sonnet-20250219-beta:0" # Cross-region inference
+    use_bedrock: "true"
+    # ... other inputs
+
+# For Google Vertex AI with OIDC
+- uses: anthropics/claude-code-action@beta
+  with:
+    model: "claude-3-7-sonnet@20250219"
+    use_vertex: "true"
+    # ... other inputs
+```
+
+## OIDC Authentication for Bedrock and Vertex
+
+Both AWS Bedrock and GCP Vertex AI require OIDC authentication.
+
+```yaml
+# For AWS Bedrock with OIDC
+- name: Configure AWS Credentials (OIDC)
+  uses: aws-actions/configure-aws-credentials@v4
+  with:
+    role-to-assume: ${{ secrets.AWS_ROLE_TO_ASSUME }}
+    aws-region: us-west-2
+
+- name: Generate GitHub App token
+  id: app-token
+  uses: actions/create-github-app-token@v2
+  with:
+    app-id: ${{ secrets.APP_ID }}
+    private-key: ${{ secrets.APP_PRIVATE_KEY }}
+
+- uses: anthropics/claude-code-action@beta
+  with:
+    model: "anthropic.claude-3-7-sonnet-20250219-beta:0"
+    use_bedrock: "true"
+    # ... other inputs
+
+  permissions:
+    id-token: write # Required for OIDC
+```
+
+```yaml
+# For GCP Vertex AI with OIDC
+- name: Authenticate to Google Cloud
+  uses: google-github-actions/auth@v2
+  with:
+    workload_identity_provider: ${{ secrets.GCP_WORKLOAD_IDENTITY_PROVIDER }}
+    service_account: ${{ secrets.GCP_SERVICE_ACCOUNT }}
+
+- name: Generate GitHub App token
+  id: app-token
+  uses: actions/create-github-app-token@v2
+  with:
+    app-id: ${{ secrets.APP_ID }}
+    private-key: ${{ secrets.APP_PRIVATE_KEY }}
+
+- uses: anthropics/claude-code-action@beta
+  with:
+    model: "claude-3-7-sonnet@20250219"
+    use_vertex: "true"
+    # ... other inputs
+
+  permissions:
+    id-token: write # Required for OIDC
+```