Leave traces on the project about the tool (spin) and template used

[danielo515]

Hello, and thank you for doing ocaml/reason development much easier to start with.
I have one old project that I didn't touched in two years. After I came back to it, it looked unfamiliar, and it contains a lot of things I didn't remember adding, like an install script and statements like "available in all major platforms". I was almost sure that I built it using a template, but I was not sure which one (or even what tool I used to bootstrap it). Today, a compliation error (that I didn't yet fixed) pointed me to an issue in this repository, and that made me remember that I actually used spin to start my project.
It will be awesome if, at the very bottom of the template's readme you leave a trace like "bootstrapped with spin", or something like that.