[DOC] Readme update

README.md

-# Gargantext Purescript
+# Gargantext with Purescript (FrontEnd instance)
 
-## About this project
+## About the project
 
-Gargantext is a collaborative web platform for the exploration of sets
-of unstructured documents. It combines tools from natural language
-processing, text-mining, complex networks analysis and interactive data
-visualization to pave the way toward new kinds of interactions with your
-digital corpora.
+GarganText is a collaborative web-decentralized-based macro-service
+platform for the exploration of unstructured texts. It combines tools
+from natural language processing, text-data-mining tricks, complex
+networks analysis algorithms and interactive data visualization tools to
+pave the way toward new kinds of interactions with your digital corpora.
 
-This repo deals with the frontend or client which needs
-a backend server running or being granted access to a
+This software is free software, developed and offered by the CNRS
+Complex Systems Institute of Paris Île-de-France (ISC-PIF) and its
+partners.
+
+GarganText Project: this repo builds the
+frontend for the backend server built by
 [backend](https://gitlab.iscpif.fr/gargantext/haskell-gargantext).
 
-This software is free software, developed by the CNRS Complex Systems
-Institute of Paris Île-de-France (ISC-PIF) and its partners.
 
 ## Getting set up
 
 There are two approaches to working with the build:
-1. Use our docker setup
+1. Use our Nix or Docker setup
 2. Install our dependencies yourself
 
-The javascript ecosystem kind of assumes if you're on linux, you're
-running on debian or ubuntu. I haven't yet managed to get garg to
-build on alpine linux, for example. If you're on an oddball system, I
-*strongly* recommend you just use the docker setup.
+### With Nix setup
+
+First install [nix](https://nixos.org/guides/install-nix.html): 
+
+```shell
+sh < (curl -L https://nixos.org/nix/install) --daemon
+```
+
+Verify the installation is complete
+```shell
+$ nix-env
+nix-env (Nix) 2.3.12
+```
+
+To build the frontend just do:
+```
+nix-shell --run build
+```
+Just serve dist/index.html with any server and you are ready to be
+connected to any backend.
+
 
-### Docker setup
+### With Docker setup
 
 You will need docker and docker-compose installed.