Add in docs/adr to ensure we capture decisions properly during design calls (#4707)

docs/adrs/001-record-architecture-decisions.md

+# 1. Record architecture decisions
+
+Date: 2021-12-09
+
+## Status
+
+Accepted
+
+## Context
+
+We need to record the architectural decisions made on this project.
+
+## Decision
+
+We will use Architecture Decision Records, as [described by Michael Nygard](http://thinkrelevance.com/blog/2011/11/15/documenting-architecture-decisions).
+
+## Consequences
+
+See Michael Nygard's article, linked above. For a lightweight ADR toolset, see Nat Pryce's [adr-tools](https://github.com/npryce/adr-tools).
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