Add Homebrew formula. (#68)

HomebrewFormula/terraform-docs.rb

@@ -0,0 +1,24 @@
+class TerraformDocs < Formula
+  desc "Tool to generate documentation from Terraform modules"
+  homepage "https://github.com/segmentio/terraform-docs"
+  url "https://github.com/segmentio/terraform-docs/archive/v0.4.5.tar.gz"
+  sha256 "78b75d3ba2525b272ae93036465bf3a5137bb259d7f7c106d026529492df2e29"
+
+  depends_on "go" => :build
+
+  def install
+    ENV["GOPATH"] = buildpath
+    dir = buildpath/"src/github.com/segmentio/terraform-docs"
+    dir.install buildpath.children
+
+    cd dir do
+      system "make", "build-darwin-amd64"
+      bin.install "bin/darwin-amd64/terraform-docs"
+      prefix.install_metafiles
+    end
+  end
+
+  test do
+    system "#{bin}/terraform-docs", "--version"
+  end
+end