correct readme

Author: MarcoGorelli

README.md

@@ -35,8 +35,10 @@ There are three steps to writing dataframe-agnostic code using Narwhals:
 3. use `narwhals.to_native` to return an object to the user in its original
    dataframe flavour. For example:
 
-   - if you started with pandas, you'll get pandas back
-   - if you started with Polars, you'll get Polars back
+   - if you started with a pandas DataFrame, you'll get a pandas DataFrame back
+   - if you started with a Polars DataFrame, you'll get a Polars DataFrame back
+   - if you started with a Polars LazyFrame, you'll get a Polars LazyFrame back (unless
+     you called `.collect`!)
 
 ## Example