docs: document releases

Signed-off-by: MarcoIeni <11428655+MarcoIeni@users.noreply.github.com>

service-catalog/releases/README.md

@@ -0,0 +1,22 @@
+# Releases
+
+Here's the infrastructure we use to distribute the Rust releases:
+
+- [release-distribution](https://github.com/rust-lang/simpleinfra/blob/master/terragrunt/modules/release-distribution/):
+  Terraform module that utilizes Cloudfront and Fastly to manage the distribution of releases via `static-rust-lang-org`.
+- [releases](https://github.com/rust-lang/simpleinfra/blob/docs-document-release-distribution/terraform/releases/):
+  Terraform module managing the infrastructure that publishes Rust releases, including [promote-release](https://github.com/rust-lang/promote-release),
+  the tool used to publish new releases of the Rust toolchain.
+
+## Versions
+
+`simpleinfra` repo:
+- Terraform providers
+
+`promote-releases` repo:
+- [Cargo.toml](https://github.com/rust-lang/promote-release/blob/master/Cargo.toml) dependencies
+- GitHub Actions: specified in the
+  [workflows](https://github.com/rust-lang/promote-release/tree/master/.github/workflows)
+  directory
+- Ubuntu version specified in the
+  [Dockerfile](https://github.com/rust-lang/promote-release/blob/master/prod/Dockerfile)