chore: add README to opencode plugin

.changeset/strong-jeans-smash.md

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+---
+'@sveltejs/opencode': patch
+---
+
+chore: add README to opencode plugin

packages/opencode/README.md

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+# @sveltejs/opencode
+
+OpenCode plugin for Svelte that provides the Svelte MCP server, a specialized file editor subagent and instruction files.
+
+## Installation
+
+Add `@sveltejs/opencode` to your OpenCode config (either global or local):
+
+```json
+{
+	"$schema": "https://opencode.ai/config.json",
+	"plugin": ["@sveltejs/opencode"]
+}
+```
+
+That's it! You now have the Svelte MCP server and the file editor subagent configured automatically.
+
+## Features
+
+### Svelte MCP Server
+
+The plugin automatically configures the [Svelte MCP server](https://mcp.svelte.dev) which provides:
+
+- **list-sections** - Discover available Svelte 5 and SvelteKit documentation sections
+- **get-documentation** - Retrieve full documentation content for specific sections
+- **svelte-autofixer** - Analyze Svelte code and get issues/suggestions
+- **playground-link** - Generate Svelte Playground links with provided code
+
+### Svelte File Editor Subagent
+
+A specialized subagent (`svelte-file-editor`) that is automatically used when creating, editing, or reviewing `.svelte`, `.svelte.ts`, or `.svelte.js` files. It fetches relevant documentation and validates code using the Svelte MCP server tools.
+
+### Agent Instructions
+
+The plugin injects instructions that teach the agent how to effectively use the Svelte MCP tools.
+
+## Configuration
+
+The default configuration:
+
+```json
+{
+	"$schema": "https://raw.githubusercontent.com/sveltejs/mcp/refs/heads/main/packages/opencode/schema.json",
+	"mcp": {
+		"type": "remote",
+		"enabled": true
+	},
+	"subagent": {
+		"enabled": true
+	},
+	"instructions": {
+		"enabled": true
+	}
+}
+```
+
+### Configuration Options
+
+| Option                 | Type                    | Default    | Description                                                                      |
+| ---------------------- | ----------------------- | ---------- | -------------------------------------------------------------------------------- |
+| `mcp.type`             | `"remote"` \| `"local"` | `"remote"` | Use the remote server at `mcp.svelte.dev` or run locally via `npx @sveltejs/mcp` |
+| `mcp.enabled`          | `boolean`               | `true`     | Enable/disable the MCP server                                                    |
+| `subagent.enabled`     | `boolean`               | `true`     | Enable/disable the Svelte file editor subagent                                   |
+| `instructions.enabled` | `boolean`               | `true`     | Enable/disable agent instructions injection                                      |
+
+### Config File Location
+
+Place your configuration at one of these locations:
+
+- `~/.config/opencode/svelte.json` (global)
+- `$OPENCODE_CONFIG_DIR/svelte.json` (if `OPENCODE_CONFIG_DIR` is set, takes priority)
+
+## License
+
+MIT