- update readme

- add install script

Author: pytlesk4

README.md

@@ -6,4 +6,22 @@ The perfect OAS (Swagger 2) companion. Turn any OAS file into an API server with
 
 [Documentation - https://designer.stoplight.io/docs/prism](https://designer.stoplight.io/docs/prism?utm_source=github&utm_medium=prism)
 
-Downloads available over in [releases](https://github.com/stoplightio/prism/releases).
+## Installation
+
+On OS X or Linux:
+
+```
+curl https://raw.githubusercontent.com/stoplightio/prism/master/install.sh | sh
+```
+
+On Windows download [binary](https://github.com/stoplightio/prism/releases).
+
+## Update
+
+```
+prism update
+```
+or
+```
+prism up
+```

install.sh

@@ -0,0 +1,41 @@
+#!/bin/sh
+
+install () {
+
+set -eu
+
+UNAME=$(uname)
+ARCH=$(uname -m)
+if [ "$UNAME" != "Linux" ] && [ "$UNAME" != "Darwin" ] && [ "$ARCH" != "x86_64" ] && [ "$ARCH" != "i686" ]; then
+    echo "Sorry, OS/Architecture not supported: ${UNAME}/${ARCH}. Download binary from https://github.com/stoplightio/prism/releases"
+    exit 1
+fi
+
+if [ "$UNAME" = "Darwin" ] ; then
+  OSX_ARCH=$(uname -m)
+  if [ "${OSX_ARCH}" = "x86_64" ] ; then
+    PLATFORM="darwin_amd64"
+  fi
+elif [ "$UNAME" = "Linux" ] ; then
+  LINUX_ARCH=$(uname -m)
+  if [ "${LINUX_ARCH}" = "i686" ] ; then
+    PLATFORM="linux_386"
+  elif [ "${LINUX_ARCH}" = "x86_64" ] ; then
+    PLATFORM="linux_amd64"
+  fi
+fi
+
+LATEST=$(curl -s https://api.github.com/repos/stoplightio/prism/tags | grep -Eo '"name":.*?[^\\]",'  | head -n 1 | sed 's/[," ]//g' | cut -d ':' -f 2)
+URL="https://github.com/stoplightio/prism/releases/download/$LATEST/prism_$PLATFORM"
+DEST=/usr/local/bin/prism
+
+if [ -z $LATEST ] ; then
+  echo "Error requesting. Download binary from ${URL}"
+  exit 1
+else
+  curl -sL $URL -o $DEST
+  chmod +x $DEST
+fi
+}
+
+install