Update README

README.md

@@ -13,3 +13,48 @@ A collection of user defined functions, from your favourite databases, in DataFu
 | JSON            | 🚧︎ Ongoing                         |
 | Built-In Scalar | ⭘  Not Started                      |
 | Maths           | ⭘  Not Started                      |
+
+## How to use
+
+Since `df_extras` is not published to crates.io yet, directly specify the git repository link
+as a dependency.
+
+```toml
+// In Cargo.toml
+[dependencies]
+datafusion = "33.0.0"
+df_extras = { features = ["postgres"], git = "https://github.com/dadepo/df_extras" }
+tokio = "1.34.0"
+```
+
+Then in code:
+
+```rust
+use datafusion::prelude::SessionContext;
+use df_extras::postgres::register_postgres_udfs;
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let ctx = SessionContext::new();
+
+    register_postgres_udfs(&ctx)?;
+
+    let df = ctx
+        .sql("select inet_merge('192.168.1.5/24', '192.168.2.5/24') as result")
+        .await?;
+
+    df.show().await?;
+
+    Ok(())
+}
+```
+
+The above will print out
+
+```
++----------------+
+| result         |
++----------------+
+| 192.168.0.0/22 |
++----------------+
+```