Sync saddle-points docs with problem-specifications (#350)

The saddle-points exercise has been overhauled as part of a project
to make practice exercises more consistent and friendly.

For more context, please see the discussion in the forum, as well as
the pull request that updated the exercise in the problem-specifications
repository:

- https://forum.exercism.org/t/new-project-making-practice-exercises-more-consistent-and-human-across-exercism/3943

exercises/practice/saddle-points/.docs/instructions.md

@@ -1,25 +1,24 @@
 # Instructions
 
-Detect saddle points in a matrix.
+Your task is to find the potential trees where you could build your tree house.
 
-So say you have a matrix like so:
+The data company provides the data as grids that show the heights of the trees.
+The rows of the grid represent the east-west direction, and the columns represent the north-south direction.
 
-```text
-    1  2  3
-  |---------
-1 | 9  8  7
-2 | 5  3  2     <--- saddle point at row 2, column 1, with value 5
-3 | 6  6  7
-```
+An acceptable tree will be the the largest in its row, while being the smallest in its column.
 
-It has a saddle point at row 2, column 1.
+A grid might not have any good trees at all.
+Or it might have one, or even several.
 
-It's called a "saddle point" because it is greater than or equal to every element in its row and less than or equal to every element in its column.
+Here is a grid that has exactly one candidate tree.
 
-A matrix may have zero or more saddle points.
+    1  2  3  4
+  |-----------
+1 | 9  8  7  8
+2 | 5  3  2  4  <--- potential tree house at row 2, column 1, for tree with height 5
+3 | 6  6  7  1
 
-Your code should be able to provide the (possibly empty) list of all the saddle points for any given matrix.
+- Row 2 has values 5, 3, and 1. The largest value is 5.
+- Column 1 has values 9, 5, and 6. The smallest value is 5.
 
-The matrix can have a different number of rows and columns (Non square).
-
-Note that you may find other definitions of matrix saddle points online, but the tests for this exercise follow the above unambiguous definition.
+So the point at `[2, 1]` (row: 2, column: 1) is a great spot for a tree house.

exercises/practice/saddle-points/.docs/introduction.md

@@ -0,0 +1,9 @@
+# Introduction
+
+You are planning on building a tree house in the woods near your house so that you can watch the sun rise and set.
+
+You've obtained data from a local survey company that shows the heights of all the trees in each rectangular section of the map.
+You need to analyze each grid on the map to find the perfect tree for your tree house.
+
+The best tree will be the tallest tree compared to all the other trees to the east and west, so that you have the best possible view of the sunrises and sunsets.
+You don't like climbing too much, so the perfect tree will also be the shortest among all the trees to the north and to the south.