Documentation missing list of available tools for --allowed-tools configuration

## Problem

The [configuration documentation](https://github.com/anthropics/claude-code-action/blob/main/docs/configuration.md) mentions the `--allowed-tools` parameter but doesn't list what tools are actually available to specify. This makes it difficult for users to configure the action properly.

The current docs show example usage like:
```yaml
claude_args: |
--allowedTools "Bash(git:*),Edit,Read"
```

But users have no reference for what other tools exist beyond the ones shown in examples.

## Suggested Solution

Add a section to the configuration documentation that lists all available built-in tools:

**File Operations:**
- `Edit` - Edit files
- `Read` - Read files
- `Write` - Write files
- `Glob` - File pattern matching
- `Grep` - Content search

**Execution:**
- `Bash` - Execute shell commands (requires pattern specification, e.g., `Bash(git:*)` or `Bash(npm install)`)

**Web:**
- `WebFetch` - Fetch web content
- `WebSearch` - Search the web

**Other:**
- `NotebookRead` / `NotebookEdit` - Work with Jupyter notebooks
- `MultiEdit` - Batch file edits

**Note:** MCP (Model Context Protocol) tools follow the pattern `mcp____`

## Additional Context

This information is available in the [Claude Code CLI reference](https://code.claude.com/docs/en/cli-reference), but users configuring the GitHub Action shouldn't need to hunt through separate documentation to find what tools they can configure.

Also worth clarifying the distinction between:
- `--allowedTools` - Tools that execute without prompting for permission
- `--tools` - Restricts which tools are available at all