Port INSTALL.md from old repo

INSTALL

@@ -1,5 +0,0 @@
-Building Zcash
-
-See the Zcash github wiki (https://github.com/zcash/zcash/wiki) for instructions on building zcashd,
-the intended-for-services, no-graphical-interface, reference
-implementation of Zcash.

INSTALL.md

@@ -0,0 +1,80 @@
+# Installing Hush
+
+## Build HUSH dependencies
+
+The following build process generally applies to Ubuntu (and similar) Linux
+distributions. For best results it is recommended to use Ubuntu Linux 16.04
+or later.
+
+## Swap Space (Optional)
+You will need at least 4GB of RAM to build hush from git source, OR you can
+enable a swap file. To enable a 4GB swap file on modern Linux distributions:
+
+```sh
+sudo fallocate -l 4G /swapfile
+sudo chmod 600 /swapfile
+sudo mkswap /swapfile
+sudo swapon /swapfile
+```
+
+## Build on Linux:
+
+
+```sh
+# install build depedencies
+sudo apt-get install build-essential pkg-config libc6-dev m4 g++-multilib \
+      autoconf libtool ncurses-dev unzip git python zlib1g-dev wget \
+      bsdmainutils automake curl unzip nano
+# pull
+git clone https://github.com/MyHush/hush3.git
+cd hush3
+# Build
+./zcutil/build.sh -j$(nproc)
+```
+
+## Download proving key:
+```sh
+./zcutil/fetch-params.sh
+```
+
+## Run a HUSH Node
+
+```sh
+./src/hushd
+```
+
+## Windows (cross-compiled on Linux)
+Get dependencies:
+```ssh
+sudo apt-get install \
+      build-essential pkg-config libc6-dev m4 g++-multilib \
+      autoconf libtool ncurses-dev unzip git python \
+      zlib1g-dev wget bsdmainutils automake mingw-w64 cmake
+```
+
+Downloading Git source repo, building and running Hush:
+
+```sh
+# pull
+git clone https://github.com/MyHush/hush3.git
+cd hush
+# fetch key
+./zcutil/fetch-params.sh
+# Build
+./zcutil/build-win.sh -j$(nproc)
+# Run a HUSH node
+./src/hushd
+```
+
+Currently Linux,  Windows and Mac OS X are our supported platforms. If you
+are interested in porting Hush to a new operating system, we are interested
+to talk with you. Experimental FreeBSD support is in progress, thanks to radix42.
+
+We aim to support all platforms, but there is only so much time in the day.
+
+Currently, any ARMv7 machine will not be able to build this repo, because the
+underlying tech (zcash and the zksnark library) do not support that instruction
+set.
+
+This also means that RaspberryPi devices will not work, unless they have a
+newer ARMv8-based Raspberry Pi.