Mention one needs first to import "base" before opening it

[ulugbekna]

It was recently a source of confusion for a new comer reading RWO on his stream - https://www.twitch.tv/theprimeagen/

[laksith19]

Hmm yea this line surely can cause some confusion as technically Base should already be opened by default if you create the ~/.ocamlinit as per the install instructions. Base is available after #require core.top.