Adds a npmignore so that you can use rootDir in a TS project with this lib

[orta]

The *.js and *.js.map files gives all the necessary details for clients to work with this library without the *.ts files. So this makes them not get shipped with the node module in npm.

Reason: I'm seeing this:

[orta]

Until then, I've got a branch others can use: yarn add json2ts@orta/json2ts#ts-less -d

[orta]

Poke