reflect comment

Signed-off-by: Mamoru Sobue <[email protected]>

autoware_lanelet2_extension/docs/extra_lanelet_subtypes.md

@@ -48,13 +48,15 @@ Sample pedestrian lane in .osm format is shown below:
 
 Although `bicycle_lane` subtype is already defined in the original [Lanelet2 documentation](https://github.com/fzi-forschungszentrum-informatik/Lanelet2/blob/master/lanelet2_core/doc/LaneletAndAreaTagging.md#subtype-and-location), Autoware compatible with `format_version>=2` supports `bicycle_lane` at component level.
 
-- refers: `road` lanelet adjacent to the objective `bicycle_lane` should share the same boundary LineString
+In Autoware, `bicycle_lane` is used to identify paths dedicated to cyclists. These lanes can assist in predicting the future paths of bicycles and indicate lanes that Autoware vehicles should avoid or keep clear of.
+
 - specification:
+  - `road` lanelet adjacent to the objective `bicycle_lane` should share the same boundary LineString
   - A `bicycle_lane` is connected to/from only `bicycle_lane` lanelets and is adjacent to a `road` lanelet. Namely in Left(Right) hand side traffic rules, it is on the left(right) side of `road` lanelet.
 - Although pullover on `bicycle_lane` is normally prohibited by the law, it is allowed to place a `road_shoulder` adjacent to a `bicycle_lane`. However the autoware implementation may not fully support appropriate behavior in such cases.
 - The treatment of _bicycle guide painting_, or the shift-arrow shaped painting on the side of the road without explicit separating line, is open to discussion. We can either identity them as part of the vehicle road or separate them as distinct bicycle lanes.
 
-![Bicycle lane](bicycle_lane.svg)
+![Bicycle lane](bicycle_lane.drawio.svg)
 
 Sample bicycle lane in .osm format is shown below: