Update readme.md

[riccardoklinger]

spatiallite is mentione as prerequisite

[fidelthomet]

Thank you for your engagement!
I find your changes a bit misleading as spatiallite gets installed by running npm install. The additional steps are only required if you're running Windows.

Can you confirm that it works on windows if you follow the instuctions on https://www.npmjs.com/package/spatialite ?

[riccardoklinger]

Installation of spatiallite via npm on ubuntu fails:
13571 error Linux 4.4.0-92-generic
13572 error argv "/usr/bin/nodejs" "/usr/bin/npm" "install" "spatialite"
13573 error node v4.4.5
13574 error npm v2.15.5
13575 error code ELIFECYCLE
13576 error [email protected] install: node-gyp rebuild
13576 error Exit status 1
13577 error Failed at the [email protected] install script 'node-gyp rebuild'.
13577 error This is most likely a problem with the spatialite package,
13577 error not with npm itself.
13577 error Tell the author that this fails on your system:
13577 error node-gyp rebuild