docs: add information about API to README.md

Author: tkskto

README.md

@@ -46,8 +46,22 @@ npm exec vca -- --dir .
 *   `-o` or `--out` : output directory. JSON file will output here.
 *   `-p` or `--port` : select a port number for the local server.
 
-## License
+## API
 
-MIT License.
+vue-component-analyzer is also available as an API from v0.6.0.
+
+This API is intended to be used for testing.
+
+```javascript
+import {getImportDeclarationTree} from '@tkskto/vue-component-analyzer';
+
+const jsonOfTree = getImportDeclarationTree('entryFile.vue');
+```
+
+See [index.d.ts](./types/index.d.ts) for details of types.
 
+(`lastModifiedTime` can be noise. If you don't need it remove explicitly.)
 
+## License
+
+MIT License.

types/index.d.ts

@@ -1,3 +1,10 @@
+/**
+ * name: filename
+ * props: props defined in the component
+ * size: filesize
+ * lastModifiedTime: date modified the file
+ * children: information array this file is importing
+ */
 export interface FileReport {
   name: string,
   props: string,