change example

Signed-off-by: Masaya Kataoka <ms.kataoka@gmail.com>

.github/pull_request_samples/example_detail.md

@@ -28,8 +28,8 @@ This PR fixes how the length of the curve is computed
 
 ## References
 
-- [Document about spline curve.](https://people.computing.clemson.edu/~dhouse/courses/405/notes/splines.pdf)
-  - This link is an example and is not directly related to this sample.
+Please check [this document about spline curve.](https://people.computing.clemson.edu/~dhouse/courses/405/notes/splines.pdf)  
+This link is an example and is not directly related to this sample.
 
 # Destructive Changes