Sketch on face of chamfer now works, added an example (#3876)

* sketch on face of chamfer example

Signed-off-by: Jess Frazelle <github@jessfraz.com>

* sketch on face of chamfer example

Signed-off-by: Jess Frazelle <github@jessfraz.com>

* make pretty

Signed-off-by: Jess Frazelle <github@jessfraz.com>

* docs

Signed-off-by: Jess Frazelle <github@jessfraz.com>

---------

Signed-off-by: Jess Frazelle <github@jessfraz.com>

src/wasm-lib/kcl/src/std/chamfer.rs

@@ -42,6 +42,7 @@ pub async fn chamfer(args: Args) -> Result<KclValue, KclError> {
 /// a sharp, straight transitional edge.
 ///
 /// ```no_run
+/// // Chamfer a mounting plate.
 /// const width = 20
 /// const length = 10
 /// const thickness = 1
@@ -65,6 +66,36 @@ pub async fn chamfer(args: Args) -> Result<KclValue, KclError> {
 ///     ],
 ///   }, %)
 /// ```
+///
+/// ```no_run
+/// // Sketch on the face of a chamfer.
+/// fn cube = (pos, scale) => {
+/// const sg = startSketchOn('XY')
+///     |> startProfileAt(pos, %)
+///     |> line([0, scale], %)
+///     |> line([scale, 0], %)
+///     |> line([0, -scale], %)
+///
+///     return sg
+/// }
+///
+/// const part001 = cube([0,0], 20)
+///     |> close(%, $line1)
+///     |> extrude(20, %)
+///     |> chamfer({
+///         length: 10,
+///         tags: [getOppositeEdge(line1)]
+///     }, %, $chamfer1) // We tag the chamfer to reference it later.
+///
+/// const sketch001 = startSketchOn(part001, chamfer1)
+///     |> startProfileAt([10, 10], %)
+///     |> line([2, 0], %)
+///     |> line([0, 2], %)
+///     |> line([-2, 0], %)
+///     |> lineTo([profileStartX(%), profileStartY(%)], %)
+///     |> close(%)
+///     |> extrude(10, %)
+/// ```
 #[stdlib {
     name = "chamfer",
 }]
@@ -111,7 +142,7 @@ async fn inner_chamfer(
                 radius: data.length,
                 tolerance: DEFAULT_TOLERANCE, // We can let the user set this in the future.
                 cut_type: Some(kittycad::types::CutType::Chamfer),
-                face_id: None,
+                face_id: Some(id),
             },
         )
         .await?;
@@ -125,7 +156,7 @@ async fn inner_chamfer(
 
         if let Some(ref tag) = tag {
             extrude_group.value.push(ExtrudeSurface::Chamfer(ChamferSurface {
-                face_id: edge_id,
+                face_id: id,
                 tag: Some(tag.clone()),
                 geo_meta: GeoMeta {
                     id,