adds tsa cert chain check for env var or tuf targets. #6837

	#
	# Copyright 2021 The Sigstore Authors.
	#
	# Licensed under the Apache License, Version 2.0 (the "License");
	# you may not use this file except in compliance with the License.
	# You may obtain a copy of the License at
	#
	# http://www.apache.org/licenses/LICENSE-2.0
	#
	# Unless required by applicable law or agreed to in writing, software
	# distributed under the License is distributed on an "AS IS" BASIS,
	# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	# See the License for the specific language governing permissions and
	# limitations under the License.

	name: Docgen

	on:
	workflow_dispatch:
	push:
	branches: ['main', 'release-*']
	pull_request:

	permissions: read-all

	jobs:
	docgen:
	name: Verify Docgen
	runs-on: ubuntu-latest

	steps:
	- name: deps
	run: sudo apt-get update && sudo apt-get install -yq libpcsclite-dev
	- uses: actions/checkout@1d96c772d19495a3b5c517cd2bc0cb401ea0529f # v4.1.3
	- uses: actions/setup-go@0c52d547c9bc32b1aa3301fd7a9cb496313a4491 # v5.0.0
	with:
	go-version: '1.21'
	check-latest: true
	- run: ./cmd/help/verify.sh

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