fix(docs): SDK key files list; README saveData uses GetConfig and Marshal

Author: Cod-e-Codes

PLUGIN_ECOSYSTEM.md

@@ -32,8 +32,7 @@ The plugin ecosystem consists of several interconnected components:
 **Purpose**: Provides the core interface and types for plugin development.
 
 **Key Files**:
-- `plugin.go` - Core Plugin interface and supporting types
-- `BasePlugin` - Default implementation for common functionality
+- `plugin.go` - Core `Plugin` interface, `BasePlugin`, and supporting types
 - `stdio.go` - Shared stdin/stdout JSON loop (`RunStdio`, `RunIO`) and `HandlePluginRequest` for init/message/command/shutdown
 
 **Features**:

plugin/README.md

@@ -288,9 +288,19 @@ type Config struct {
 Plugins can store data in their data directory:
 
 ```go
+import (
+    "encoding/json"
+    "os"
+    "path/filepath"
+)
+
 func (p *MyPlugin) saveData(data interface{}) error {
-    dataFile := filepath.Join(p.config.DataDir, "data.json")
-    return os.WriteFile(dataFile, data, 0644)
+    dataFile := filepath.Join(p.GetConfig().DataDir, "data.json")
+    b, err := json.Marshal(data)
+    if err != nil {
+        return err
+    }
+    return os.WriteFile(dataFile, b, 0644)
 }
 ```