Adding missing README update

Author: ozten

day_12_hill_climbing_algorithm/README.md

@@ -42,4 +42,40 @@ What is the fewest steps required to move from your current position to the loca
 
 To begin, get your puzzle input.
 
-Answer:
+Answer:
+
+## Part Two
+
+As you walk up the hill, you suspect that the Elves will want to turn this into a hiking trail. The beginning isn't very scenic, though; perhaps you can find a better starting point.
+
+To maximize exercise while hiking, the trail should start as low as possible: elevation a. The goal is still the square marked E. However, the trail should still be direct, taking the fewest steps to reach its goal. So, you'll need to find the shortest path from any square at elevation a to the square marked E.
+
+Again consider the example from above:
+
+Sabqponm
+abcryxxl
+accszExk
+acctuvwj
+abdefghi
+
+Now, there are six choices for starting position (five marked a, plus the square marked S that counts as being at elevation a). If you start at the bottom-left square, you can reach the goal most quickly:
+
+...v<<<<
+...vv<<^
+...v>E^^
+.>v>>>^^
+>^>>>>>^
+
+This path reaches the goal in only 29 steps, the fewest possible.
+
+What is the fewest steps required to move starting from any square with elevation a to the location that should get the best signal?
+
+Your puzzle answer was 345.
+
+Both parts of this puzzle are complete! They provide two gold stars: **
+
+At this point, you should return to your Advent calendar and try another puzzle.
+
+If you still want to see it, you can get your puzzle input.
+
+You can also [Shareon Twitter Mastodon] this puzzle.