remove ws and update export to

README.md

@@ -14,6 +14,22 @@ Online at: https://parquet-viewer.xiangpeng.systems
 
 ![screenshot](doc/parquet-viewer.gif)
 
+### Headless mode
+Despite being a battery-included web app, it can also be used as a headless tool, especially helpful when working with LLM tools.
+
+Like command args for CLI tools, you can pass url params to control the behavior of the app.
+
+For example, [this link](https://parquet-viewer.xiangpeng.systems/?tab=url&url=https%3A%2F%2Fraw.githubusercontent.com%2Ftobilg%2Fpublic-cloud-provider-ip-ranges%2Fmain%2Fdata%2Fproviders%2Fall.parquet&query=SELECT%20%22cloud_provider%22%2C%20%22region%22%2C%20SUM(%22ip_address_cnt%22)%20AS%20%22ip_count%22%20FROM%20%22all%22%20GROUP%20BY%20%22cloud_provider%22%2C%20%22region%22%20ORDER%20BY%20%22ip_count%22%20DESC%3B&export=csv) tells parquet-viewer to 
+
+(1) load a file from a url, 
+
+(2) run a SQL query (or natural language if you like), 
+
+(3) export the results to a CSV file. 
+
+Most of the query params are reflected in the URL as you operate on the app, so you can simply share the URL with others to reproduce your findings.
+
+Adding `export=csv` or `export=parquet` to the URL will export the query result to a CSV/Parquet file.
 
 
 ## Development