Intro should explain what Melange/Reason/Ocaml are and why they're worth learning

[adamsmasher]

Right now the intro starts with the premise that the reader knows what Melange and Reason and Ocaml are and what they're for. But if the intended audience is React developers, they may not have a clear idea - it's worth being explicit here. Even many people familiar with Reason or Ocaml might not know what Melange is or be confused by its relationship to Reason (or by Reason's relationship to Ocaml, or by Reason's relationship to Rescript...).

Moreover, this is probably a good place to sell the curious React developer on the advantages of the ecosystem.

For example, look at PureScript by Example - the Introduction starts by saying

PureScript is a small, strongly, statically typed programming language with expressive types, written in and inspired by Haskell, and compiling to Javascript.

Functional programming in JavaScript has seen quite a lot of popularity recently, but large-scale application development is hindered by the lack of a disciplined environment in which to write code. PureScript aims to solve that problem by bringing the power of strongly-typed functional programming to the world of JavaScript development.

Especially in the internet age, when we might want to publish this to reddit/HN or whatever and get clicks from people who don't know what they're clicking on, answering this straightaway and "selling" the technology to them might be helpful.

[feihong]

@adamsmasher I tried to address it in #60, can you take a look?