Document team structure and functions

The structure of the infra-team with its three sub-teams and who
currently holds important functions have been documented in the README.

README.md

@@ -1,7 +1,34 @@
 # Rust Infrastructure Team
 
-This repository is the home of the [Rust Infrastructure Team]. It contains
-internal documentation about the team's processes and services.
+_Managing the infrastructure supporting the Rust project itself, including CI,
+releases, bots, and metrics_
+
+The [Infrastructure Team] is one of the teams of the [Rust Project], tasked with
+managing the project's infrastructure. This repository contains internal
+documentation about the team's processes and services.
+
+## Structure
+
+The [Infrastructure Team] has three sub-teams:
+
+```mermaid
+flowchart TD
+  infra(Infrastructure team)---bootstrap(Bootstrap team)
+  infra---release(Release team)
+  infra---triagebot(Triagebot team)
+```
+
+## Functions
+
+<!-- markdownlint-disable MD013 -->
+
+| Role                   | Team member                                            |
+| ---------------------- | ------------------------------------------------------ |
+| Co-lead                | [@jdno](https://github.com/jdno)                       |
+| Co-lead                | [@shepmaster](https://github.com/shepmaster)           |
+| Council Representative | [@Mark-Simulacrum](https://github.com/mark-simulacrum) |
+
+<!-- markdownlint-enable MD013 -->
 
 ## Meetings
 
@@ -12,4 +39,5 @@ internal documentation about the team's processes and services.
 The contents of this repository are dual-licensed under the terms of the
 [MIT](./LICENSE-MIT) and the [Apache 2.0](./LICENSE-APACHE) licenses.
 
-[rust infrastructure team]: https://www.rust-lang.org/governance/teams/infra
+[infrastructure team]: https://www.rust-lang.org/governance/teams/infra
+[rust project]: https://www.rust-lang.org/