Update README for release (#549)

* Update the design doc link to one without approvals
* Add information on the public instance
* Include installation info
* Add developer documentation

Signed-off-by: Hayden <[email protected]>

Author: haydentherapper

README.md

@@ -1,11 +1,80 @@
-# Rekor on Tiles
+# Rekor v2
 
-Rekor on Tiles, aka Rekor v2, is a redesigned and modernized [Rekor](https://github.com/sigstore/rekor),
+Rekor v2, aka rekor-tiles or Rekor on Tiles, is a redesigned and modernized [Rekor](https://github.com/sigstore/rekor),
 Sigstore's signature transparency log, transitioning its backend to a modern,
 [tile-backed transparency log](https://transparency.dev/articles/tile-based-logs/) implementation to
 simplify maintenance and lower operational costs.
 
 More information (documents are shared with [sigstore-dev](https://groups.google.com/g/sigstore-dev), join the group to get access):
 
 * [Proposal](https://docs.google.com/document/d/1Mi9OhzrucIyt-UCLk_FxO2_xSQZW9ow9U3Lv0ZB_PpM/edit?resourcekey=0-4rPbZPyCS7QDj26Hk0UyvA&tab=t.0#heading=h.bjitqo6lwsmn)
-* [Design doc](https://docs.google.com/document/d/1qZ-lkpbQkBzV45rtemWYmT6ReqCwjTt5TbMDFLdaPyM/edit?resourcekey=0-bMAyN9EKPDvB0H3edYi_Cw&tab=t.0#heading=h.xzptrog8pyxf)
+* [Design doc](https://docs.google.com/document/d/1ZYlt_VFB-lxbZCcTZHN-6KVDox3h7-ePp85pNpOUF1U/edit?resourcekey=0-V3WqDB22nOJfI4lTs59RVQ&tab=t.0#heading=h.xzptrog8pyxf)
+
+## Public-good instance
+
+The Sigstore community hosts a productionized instance of Rekor v2 with a 99.5% availability SLO.
+See the [status page](https://status.sigstore.dev/) for uptime metrics.
+
+Use the public-good instance's TUF repository to determine the URL of the active instance.
+Note that the community instance's URL will change approximately every 6 months when
+we "shard" the log, creating a new log instance to keep the size of the log maintainable.
+Sigstore clients will pull the latest log shard URL from the TUF-distributed
+[SigningConfig](https://github.com/sigstore/root-signing/blob/main/targets/signing_config.v0.2.json),
+and will fetch both active and inactive shard public keys from the
+[TrustedRoot](https://github.com/sigstore/root-signing/blob/main/targets/trusted_root.json).
+
+As of October 2025, we have not yet distributed the current Rekor v2 URL in the SigningConfig, to give users
+adequate time to update their clients to support verifying entries from Rekor v2. We are planning to distribute
+the latest Rekor v2 URL by end of 2025/early 2026.
+
+If you want to start using Rekor v2, construct a signing config, using the
+[TUF-distributed signing config](https://github.com/sigstore/root-signing/blob/main/targets/signing_config.v0.2.json)
+as a base, and adding the following instance as the first entry in the `rekorTlogUrls` list:
+
+```
+    {
+      "url": "https://log2025-1.rekor.sigstore.dev",
+      "majorApiVersion": 2,
+      "validFor": {
+        "start": "2025-10-06T00:00:00Z"
+      },
+      "operator": "sigstore.dev"
+    },
+```
+
+**Note**: We will eventually turn down the 2025 Rekor v2 instance when we deploy a 2026 instance. We strongly
+advise against hardcoding this URL into any pipelines that cannot be easily updated.
+
+## Installation
+
+We provide prebuilt binaries and containers for private deployments.
+
+* Download the latest binary from [Releases](https://github.com/sigstore/rekor-tiles/releases)
+* Pull the latest container from [GHCR](https://github.com/sigstore/rekor-tiles/pkgs/container/rekor-tiles)
+* Install Rekor v2 via [Helm](https://github.com/sigstore/helm-charts/tree/main/charts/rekor-tiles)
+
+## Security Reports
+
+If you find any issues, follow Sigstore's [security policy](https://github.com/sigstore/rekor-tiles/security/policy)
+to report them.
+
+## Local Development
+
+### Deployment
+
+Run `docker compose up --build --wait` to start the service along with emulated Google Cloud Storage and Spanner instances.
+
+Run `docker compose down` to turn down the service, or `docker compose down --volumes` to turn down the service and delete
+persisted tiles.
+
+### Making a request
+
+Follow the [client documentation](https://github.com/sigstore/rekor-tiles/blob/main/CLIENTS.md#rekor-v2-the-bash-way)
+for constructing a request and parsing a response.
+
+### Testing
+
+Run unit tests with `go test ./...`.
+
+Follow the [end-to-end test documentation](https://github.com/sigstore/rekor-tiles/blob/main/tests/README.md)
+for how to run integration tests against a local instance.