Check that the taxonomy values defined in an article are authorized

To make sure that every article is using the same set of values, we should check that the values defined in an article are "authorized".

We can enforce that the value of the neo4j-version attribute, the category attribute, and the environment attribute matches a value in an authoritative list of values.

The tag attribute might be more difficult to coerce as there's already a lot of different values.

For reference, here's a summary of the current usage:

developer_tag
[cypher:52, configuration:23, performance:19, logging:19, apoc:17, cluster:14, causal-cluster:14, backup:14, bolt:13, security:13, server:13, import:12, installation:11, memory:11, operations:11, upgrade:10, browser:10, monitoring:10, load-csv:9, sql:8, linux:8, transaction:8, jvm:7, tls:7, procedures:7, heap:7, docker:7, disk:6, unix:6, indexing:6, cypher-shell:6, garbage-collection:5, http:5, jdbc:5, tableau:5, consistency:5, desktop:5, startup:5, drivers:5, cpu:5, storage:4, store:4, visualization:4, bi-connector:4, exception:4, connection:4, neo4j-admin:4, csv:4, ssl:4, lock:4, out-of-memory:4, authentication:4, java:4, embedded:4, aws:4, path:4, temporal:4, timeout:3, open-files:3, ha:3, https:3, cache:3, constraint:3, encryption:3, page-cache:3, debian:3, routing:3, metrics:3, permissions:3, leader:3, follower:3, quotes:3, writes:3, merge:3, user:3, query-log:3, parameters:3, ports:3, filesystem:2, causal:2, load-balancer:2, version:2, fulltext:2, ldap:2, warmup:2, relationships:2, cardinality:2, error:2, certificate:2, ubuntu:2, jdk:2, tuning:2, websocket:2, sysinfo:2, webserver:2, master:2, delete:2, java-api:2, extension:2, samaccountname:2, account:2, authorization:2, counts:2, dump:2, plugin:2, export:2, deadlock:2, multi-datacenter:2, user-agent:2, cli:2, support:2, jmx:2, query:2, commit:2, cloud:2, neo4j-import:2, json:2, copy:2, debug:2, logs:2, enterprise:2, metadata:2, rest:2, properties:2, schema:2, disk-space:2, union:2, core:2, pid:2, thread:2, python:2, s3:2, shutdown:2, latency:2, url:2, capacity:1, election:1, index:1, search:1, kernel:1, scaling:1, labels:1, migration:1, grouping:1, compaction:1, soundex:1, conditional:1, ha-proxy:1, shell:1, bloom:1, perspectives:1, recovery:1, garbage-collector:1, jre:1, java11:1, write:1, read:1, match:1, slave:1, kubernetes:1, load:1, checkpoint:1, pruning:1, explain:1, profile:1, database-growth:1, copy-store:1, file-system:1, etl:1, rdbms:1, bookmarks:1, database:1, relationship:1, record-id:1, network:1, maven:1, user-defined-procedures:1, dependencies:1, functions:1, deployment:1, delimiter:1, neo4j-conf:1, debug-log:1, intersection:1, suspend:1, activate:1, tools:1, unwind:1, shortest-path:1, heap-dump:1, where:1, service-id:1, service:1, refactoring:1, internet-explorer:1, parameters-query-log:1, rbac:1, multi-database:1, rpm:1, logservice:1, start:1, permission-denied:1, certificates:1, client:1, plan-cache:1, cancel:1, upload:1, download:1, tcp:1, limit:1, consistency-check:1, oom:1, import-export:1, ip-address:1, hostname:1, shared:1, exclusive:1, unmanaged:1, role:1, neo4j-shell:1, host:1, nat:1, tunnel:1, transaction-log:1, linkurious:1, hardware:1, planning:1, ram:1, cipher:1, chrome:1, bookmark:1, zoom:1, edition:1, timezone:1, troubleshooting:1, offline:1, lucence:1, install:1, intellij:1, aggregations:1, max:1, min:1, restore:1]

---
developer_category
[operations:116, cypher:55, cluster:25, installation:17, import-export:16, drivers:11, browser:10, development:7, tools:6, desktop:6, performance:5, security:5, server:3, bloom:1, support:1, geospatial:1]

---
neo4j_version
[3-5:125, 3-4:124, 3-2:103, 3-3:101, 3-1:93, 3-0:85, 2-3:42, 4-0:33, 2-2:23, 2-1:10, all:5, 2-0:5, 2-x:4, 4-1:4, neo4j-desktop-1-x:3, 3-x:1, 4-x:1, neo4j-python-driver-1-2:1]

---
environment
[linux:10, docker:5, debian:4, osx:2, unix:2, kubernetes:1, desktop:1, ubuntu:1, windows:1, aws:1]

@jexp who should make the decision about which values are allowed and which values are not?

No files, tests, or entry points are identified. Start by locating where article taxonomy attributes are parsed or validated, then determine how authoritative values would be selected for neo4j-version, category, and environment; done requires an agreed list and checks for unauthorized values, with the tag decision resolved.