Add more ladder links

Author: dobromirmontauk

recipes/management/increasing_the_capacity_to_win/growing/expectations/ladders/README.md

@@ -15,3 +15,6 @@ I split my engineering ladder into the 3 main dimensions of software engineering
 * Agnes PM career ladder [here](https://docs.google.com/document/d/1EQRuoIi8F3gBCP8AJJOT5P2EOBKURYyg24iIjjGjxX8/edit#heading=h.clb9twl656u4) -- need permission to publish
 * Will Cole Mashgin PM ladder [here](https://docs.google.com/spreadsheets/d/1eWRJG-OfRqd6T_lpxd0FZZv79qYDzCcSuiNwgsrTqMo/edit?gid=1392224708#gid=1392224708)
 * Shreyas PM ladder [here](https://coda.io/@shreyas/evaluating-pm-performance)
+* https://progression.fyi/ -- good collection of 3rd party ladders
+* https://www.engineeringladders.com/ - good framework to re-use for ladders
+* https://roadmap.sh/ -- One of the top projects on Gitlab. Less of a "ladder" and more of a "how to develop these skills" -- should move elsewhere.