Update readme to reflect masters current state.

Author: pmienk

README.md

@@ -1,36 +1 @@
-[![Build Status](https://travis-ci.org/libbitcoin/libbitcoin-database.svg?branch=master)](https://travis-ci.org/libbitcoin/libbitcoin-database)
-
-[![Coverage Status](https://coveralls.io/repos/libbitcoin/libbitcoin-database/badge.svg)](https://coveralls.io/r/libbitcoin/libbitcoin-database)
-
-# Libbitcoin Database
-
-*Bitcoin High Performance Blockchain Database*
-
-Make sure you have installed [libbitcoin](https://github.com/libbitcoin/libbitcoin-system) beforehand according to its build instructions.
-
-```sh
-$ ./autogen.sh
-$ ./configure
-$ make
-$ sudo make install
-$ sudo ldconfig
-```
-
-libbitcoin-database is now installed in `/usr/local/`.
-
-**About Libbitcoin Database**
-
-Libbitcoin Database is a custom database build directly on the operating system's [memory-mapped file](https://en.wikipedia.org/wiki/Memory-mapped_file) system. All primary tables and indexes are built on in-memory hash tables, resulting in constant-time lookups. The database uses [sequence locking](https://en.wikipedia.org/wiki/Seqlock) to avoid blocking the writer. This is ideal for a high performance blockchain server as reads are significantly more frequent than writes and yet writes must proceed without delay. The [libbitcoin-blockchain](https://github.com/libbitcoin/libbitcoin-blockchain) library uses the database as its blockchain store.
-
-## Installation
-
-### Macintosh
-
-#### Using Homebrew
-
-##### Installing from Formula
-
-Instead of building, libbitcoin-database can be installed from a formula:
-```sh
-$ brew install libbitcoin-database
-```
+This branch is not usable in its current state. Please see [version3](https://github.com/libbitcoin/libbitcoin-database/tree/version3) for the latest functional branch.