Add python troubleshooting advice

Author: ston1x

README.md

@@ -16,6 +16,8 @@ If you are having issues with `guard`, just use `nanoc compile` and `nanoc view`
 The `crash.log` could provide useful information as well.
 If you see the `json` examples not changing, just delete the output folder and regenerate it with `nanoc compile`.
 
+If you are having issues with `python` 2.x being required or command/env `python` not found during `nanoc compile`, try setting up pyenv and python 2.7.18 and use it locally for this project.
+
 ## Publishing
 
 Make sure to be on the master branch and having pulled the latest changes, then run `bundle exec rake publish` from your local machine.