Remove unused docs preview tooling

The makefile used to have a target for generating docs, but it broke a long time ago. Since no one has fixed it for a long time, it must not be that critical. Removing it, so that it doesn't confuse contributors.

GNUmakefile

@@ -1,6 +1,5 @@
 TEST?=$$(go list ./... |grep -v 'vendor')
 GOFMT_FILES?=$$(find . -name '*.go' |grep -v vendor)
-WEBSITE_REPO=github.com/hashicorp/terraform-website
 PKG_NAME=tfe
 
 default: terraform-provider-tfe
@@ -64,12 +63,5 @@ test-compile:
 	fi
 	go test -c $(TEST) $(TESTARGS)
 
-website:
-ifeq (,$(wildcard $(GOPATH)/src/$(WEBSITE_REPO)))
-	echo "$(WEBSITE_REPO) not found in your GOPATH (necessary for layouts and assets), get-ting..."
-	git clone https://$(WEBSITE_REPO) $(GOPATH)/src/$(WEBSITE_REPO)
-endif
-	@$(MAKE) -C $(GOPATH)/src/$(WEBSITE_REPO) website-provider PROVIDER_PATH=$(shell pwd) PROVIDER_NAME=$(PKG_NAME)
-
-.PHONY: build test testacc vet fmt fmtcheck errcheck test-compile website sweep
+.PHONY: build test testacc vet fmt fmtcheck errcheck test-compile sweep