crypto: update README, docs

Signed-off-by: Eric Lagergren <[email protected]>

README.md

@@ -1,2 +1,6 @@
 # crypto
 SpiderOak's Cryptography Libraries
+
+## Security
+
+See our [security policy](https://github.com/aranya-project/crypto/security/policy).

crates/crypto/Cargo.toml

@@ -1,11 +1,13 @@
 [package]
 name = "spideroak-crypto"
 description = "SpiderOak's cryptography library"
-version = "0.2.0"
+version = "0.2.1"
 authors.workspace = true
 edition.workspace = true
 license = "BSD-3-Clause"
+readme = "README.md"
 repository.workspace = true
+documentation = "https://docs.rs/spideroak-crypto"
 rust-version.workspace = true
 categories = ["cryptography", "no-std", "no-std::no-alloc"]
 keywords = ["crypto", "cryptography", "spideroak"]

crates/crypto/README.md

@@ -0,0 +1,34 @@
+# `spideroak-crypto`
+
+[![Docs][docs-img]][docs-link]
+
+SpiderOak's cryptography library.
+
+## Usage
+
+This is a low-level cryptography library and can very easily be
+misued. See usage-specific guidance below.
+
+### Aranya Users
+
+Unless you are implementing an `Engine`, you should use
+[`aranya-crypto`] instead.
+
+### SpiderOak Employees
+
+Most projects have their own high-level cryptography APIs. Use
+those instead.
+
+## Security
+
+See our [security policy].
+
+[Aranya Core]: https://github.com/aranya-project/aranya
+[Aranya]: https://github.com/aranya-project/aranya
+[`aranya-crypto`]: https://crates.io/crates/aranya-crypto
+[security policy]: https://github.com/aranya-project/aranya
+
+[//]: # (badges)
+
+[docs-img]: https://docs.rs/spideroak-crypto/badge.svg
+[docs-link]: https://docs.rs/spideroak-crypto