[DOC] remove mattermost references #336

	# Licensed to the Apache Software Foundation (ASF) under one or more
	# contributor license agreements. See the NOTICE file distributed with
	# this work for additional information regarding copyright ownership.
	# The ASF licenses this file to You 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: Assign Milestone to pull request
	on:
	pull_request_target:
	types:
	- closed

	jobs:
	assign:
	name: Add milestone to closed PR
	runs-on: ubuntu-latest
	if: github.event.pull_request.merged
	steps:
	- name: add milestone
	uses: actions/github-script@v7
	with:
	github-token: ${{secrets.GITHUB_TOKEN}}
	script: \|
	github.rest.issues.update({
	issue_number: context.issue.number,
	owner: context.repo.owner,
	repo: context.repo.repo,
	milestone: null
	});

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