Improve documentation for Side and ellipse perimeter

Updated docstring for Side class and added reference for ellipse perimeter calculation.

Author: cclauss

geometry/geometry.py

@@ -53,7 +53,7 @@ def from_radians(cls, radians: float) -> Angle:
 @dataclass
 class Side:
     """
-    A side of a two dimensional Shape such as Polygon, etc.
+    A side of a two-dimensional shape such as Polygon, etc.
     adjacent_sides: a list of sides which are adjacent to the current side
     angle: the angle in degrees between each adjacent side
     length: the length of the current side in meters
@@ -118,14 +118,15 @@ def area(self) -> float:
     @property
     def perimeter(self) -> float:
         """
+        Use Ramanujan's first approximation for ellipse perimeter.
+        https://en.wikipedia.org/wiki/Perimeter_of_an_ellipse#First_approximation
+
         >>> Ellipse(5, 10).perimeter
         48.44210548835644
         >>> Ellipse(1, 10).perimeter
-        48.44210548835644
+        40.60552518514097
         """
         a, b = self.major_radius, self.minor_radius
-        # Use Ramanujan's first approximation for ellipse perimeter
-        # https://en.wikipedia.org/wiki/Perimeter_of_an_ellipse#First_approximation
         return math.pi * (3 * (a + b) - ((3 * a + b) * (a + 3 * b)) ** 0.5)
 
     @property