docs(rust): fill missing fill_null strategies (#11751)

crates/polars-core/src/chunked_array/ops/fill_null.rs

@@ -20,6 +20,10 @@ impl Series {
     /// * Mean fill (replace None with the mean of the whole array)
     /// * Min fill (replace None with the minimum of the whole array)
     /// * Max fill (replace None with the maximum of the whole array)
+    /// * Zero fill (replace None with the value zero)
+    /// * One fill (replace None with the value one)
+    /// * MinBound fill (replace with the minimum of that data type)
+    /// * MaxBound fill (replace with the maximum of that data type)
     ///
     /// *NOTE: If you want to fill the Nones with a value use the
     /// [`fill_null` operation on `ChunkedArray<T>`](crate::chunked_array::ops::ChunkFillNullValue)*.
@@ -46,6 +50,18 @@ impl Series {
     ///     let filled = s.fill_null(FillNullStrategy::Mean)?;
     ///     assert_eq!(Vec::from(filled.i32()?), &[Some(1), Some(1), Some(2)]);
     ///
+    ///     let filled = s.fill_null(FillNullStrategy::Zero)?;
+    ///     assert_eq!(Vec::from(filled.i32()?), &[Some(1), Some(0), Some(2)]);
+    ///
+    ///     let filled = s.fill_null(FillNullStrategy::One)?;
+    ///     assert_eq!(Vec::from(filled.i32()?), &[Some(1), Some(1), Some(2)]);
+    ///
+    ///     let filled = s.fill_null(FillNullStrategy::MinBound)?;
+    ///     assert_eq!(Vec::from(filled.i32()?), &[Some(1), Some(-2147483648), Some(2)]);
+    ///
+    ///     let filled = s.fill_null(FillNullStrategy::MaxBound)?;
+    ///     assert_eq!(Vec::from(filled.i32()?), &[Some(1), Some(2147483647), Some(2)]);
+    ///
     ///     Ok(())
     /// }
     /// example();