doc: add a short TEA profiles note

doc/profiles.md

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+# TEA Profiles
+
+The base TEA specification defines the common contract. Some deployments need a
+more specific subset or a stricter operating baseline. A TEA profile is a named
+set of constraints and guidance applied on top of that base contract.
+
+This is similar in spirit to a tailoring layer, as used by OSCAL profiles, but
+applied to TEA APIs, messages, and deployment expectations.
+
+## Why profiles exist
+
+Profiles let TEA stay small and interoperable while still allowing communities
+to publish sharper guidance for a given environment.
+
+A profile can:
+
+- require a subset of TEA capabilities
+- tighten transport or authentication expectations
+- add validation or lifecycle rules for a deployment community
+- document interoperability expectations without redefining the base model
+
+## Profile rules
+
+A TEA profile:
+
+- MUST identify the TEA version it applies to
+- MAY tighten requirements from the base specification
+- MUST NOT change the meaning of core fields or RPCs
+- SHOULD describe any added transport, security, or operational rules as
+  profile-level guidance rather than changing the base contract
+
+## Examples
+
+Possible TEA profiles include:
+
+- a minimal discovery and consumer profile
+- a publisher API profile
+- a regulated deployment profile with stricter transport requirements
+
+## Security and transport
+
+Transport and authentication baselines vary by deployment. For example, a
+higher-assurance profile may require mutual TLS, a specific TLS baseline, or a
+particular identity-mapping process.
+
+Those requirements should generally live in a TEA profile or deployment
+baseline, not in the base TEA contract, when they are environment-specific.