[doc] add warning about limitations of to_python depending on the python version

docs/other.rst

@@ -312,6 +312,14 @@ expect the number of spaces to add or to remove as first argument.
 .to_python()
 ------------
+.. WARNING::
+
+   Since RedBaron calls `literal_eval` it can only parse the python code parsed
+   by the python version you are using.
+
+   For example if you are using a python version inferior to 3.6, `to_python`
+   will crash on `100_000` because it is only supported since python 3.6
+
 This method safely evaluate the current selected nodes. It wraps
 `ast.literal_eval
 <https://docs.python.org/2/library/ast.html#ast.literal_eval>`_, therefor, and