[Docs] Update to the latest `mkdocs-material` and add the `contributing/DOCS.md` #5813

Job	Run time
compute-version	3s
build-docs / build-docs	1m 32s
build-artifacts / gateway-build	9s
build-artifacts / code-lint	43s
build-artifacts / frontend-build	11s
build-artifacts / runner-test (macos-latest)	1m 30s
build-artifacts / runner-test (ubuntu-latest)	53s
build-artifacts / generate-json-schema	19s
build-artifacts / python-build	25s
build-artifacts / python-test (macos-latest, 3.12)	3m 23s
build-artifacts / python-test (macos-latest, 3.9)	2m 7s
build-artifacts / python-test (ubuntu-latest, 3.9)	4m 0s
build-artifacts / python-test (ubuntu-latest, 3.10)	4m 8s
build-artifacts / python-test (ubuntu-latest, 3.13)	3m 54s
build-artifacts / python-test (macos-latest, 3.13)	3m 26s
build-artifacts / python-test (ubuntu-latest, 3.12)	4m 7s
build-artifacts / python-test (ubuntu-latest, 3.11)	4m 10s
build-artifacts / python-test (macos-latest, 3.10)	2m 37s
build-artifacts / python-test (macos-latest, 3.11)	2m 52s
build-artifacts / python-test (windows-latest, 3.9)	1m 51s
build-artifacts / python-test (windows-latest, 3.12)	1m 57s
build-artifacts / python-test (windows-latest, 3.10)	2m 2s
build-artifacts / python-test (windows-latest, 3.13)	2m 15s
build-artifacts / python-test (windows-latest, 3.11)	2m 6s
build-artifacts / runner-compile (ubuntu-24.04, linux, amd64)	35s
build-artifacts / runner-compile (ubuntu-24.04-arm, linux, arm64)	49s
upload-pre-pypi-artifacts / upload-pre-pypi-artifacts	18s
upload-post-pypi-artifacts / upload-post-pypi-artifacts	19s
	52m 41s

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