Add note on Node Versions

[RichardLitt]

Right now, this has been tested on v11.14. All other versions are suspect.

[kvutien]

I'm doing the tutorial on node v12.18.4 and it seems fine until now (01_Basics.md)

The reason for my using node 12.18.4 is that it's the latest node with which @truffle/hdwallet-provider is compatible, for my own needs with truffle.

I added this version of node in the PR of the updated 01_Basic.md