Improve readme for file

README.md

@@ -23,6 +23,8 @@ npm i @jacksontian/kimi # for scripting
 
 ```sh
 $ kimi
+Welcome to KIMI CLI(v1.0.0), type .help for more information.
+Current model is moonshot-v1-128k.
 What is your query: 写一首七言唐诗
 春风拂面桃花开，
 绿水青山共舞来。
@@ -36,6 +38,47 @@ What is your query: 写一首七言唐诗
 [Verbose] request id: chatcmpl-5cc0493c22fb4268b0772b08300886b1, usage tokens: 62
 ```
 
+### File helper
+
+We support a tiny command to manage files.
+
+```bash
+$ kimi-file # list all files
+| id                   | filename                       | purpose      | type | size       | created_at          | status |
+| -------------------- | ------------------------------ | ------------ | ---- | ---------- | ------------------- | ------ |
+| co6efvg3r07e3eepmxxx | 1906.08237.pdf                 | file-extract | file | 761790     | 2024-04-03 05:24:14 | ok     |
+$ kimi-file upload ~/xxx/test.pdf   # upload file
+$ kimi-file get the-file-id         # get file
+$ kimi-file rm the-file-id          # delete file
+```
+
+You can use `.add_file` command to choose a uploaded file:
+
+```bash
+$ kimi
+Welcome to KIMI CLI(v1.0.0), type .help for more information.
+Current model is moonshot-v1-128k.
+What is your query: .add_file
+? Please select your file: (Use arrow keys)
+? Please select your file: 1906.08237.pdf
+The file 1906.08237.pdf is added into chat session.
+What is your query: 请解读 1906.08237.pdf 文件内容
+```
+
+### Switch model
+
+You can use `.set_model` command to switch models:
+
+```bash
+$ kimi
+Welcome to KIMI CLI(v1.0.0), type .help for more information.
+Current model is moonshot-v1-128k.
+What is your query: .set_model
+? Please select your model: 
+? Please select your model: moonshot-v1-32k
+The model is switched to moonshot-v1-32k now.
+```
+
 ## Usage for scripting
 
 ```js