env for shebang and add freebsd to install script

Shebang shouldnt hardcode path to /bin/bash since some *nix flavors
dont ship with bash or install it in a different path.

install-binary.sh which is used by the helm plugin system was updated
for a freebsd binary support. This should be functional when the
first release for helm-diff is released for freebsd.

Author: sarcasticadmin

install-binary.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 # Shamelessly copied from https://github.com/technosophos/helm-template
 
@@ -52,7 +52,7 @@ initOS() {
 # verifySupported checks that the os/arch combination is supported for
 # binary builds.
 verifySupported() {
-  local supported="linux-amd64\nmacos-amd64\nwindows-amd64"
+  local supported="linux-amd64\nfreebsd-amd64\nmacos-amd64\nwindows-amd64"
   if ! echo "${supported}" | grep -q "${OS}-${ARCH}"; then
     echo "No prebuild binary for ${OS}-${ARCH}."
     exit 1