Add guide-cargo

src/SUMMARY.md

@@ -9,6 +9,7 @@
     - [Random generators](crates-gen.md)
 
 - [Guide](guide.md)
+    - [Cargo and features](guide-cargo.md)
     - [Random data](guide-data.md)
     - [Types of generators](guide-gen.md)
     - [Our RNGs](guide-rngs.md)

src/guide-cargo.md

@@ -0,0 +1,39 @@
+# Cargo and features
+
+The latest version of rand is available here: <https://crates.io/crates/rand>
+
+On the same page, and also from the repository's README, you can see documentation
+of the [Crate Features](https://github.com/rust-random/rand#crate-features).
+In particular, you may want to use the `small_rng` feature to enable the `SmallRng` generator.
+
+To add this dependency on Rand from the console, type:
+```sh
+cargo add rand --features small_rng
+```
+
+Or, add this to your `Cargo.toml`, under `[dependencies]`:
+```toml
+rand = { version = "0.8.5", features = ["small_rng"] }
+```
+
+Note: using `version = "0.8.5"` matches version `0.8.5`, `0.8.6`, etc., but not `0.9`.
+Using instead `version = "0.8"` will match any `0.8.x` version. In both cases,
+Cargo will normally install the latest matching version when the dependency is
+first added. Dependencies may be updated later via `cargo update`, and in some
+cases running `cargo update` can solve dependency problems.
+
+For more on Cargo, see [The Cargo Book](https://doc.rust-lang.org/cargo/index.html).
+
+## Other crates
+
+As noted on the [Crates](crates.md) page, the Rand library consists of a family of crates.
+To run the examples in this guide, ensure you have the following dependencies
+in your `Cargo.toml`:
+```toml
+[dependencies]
+rand = { version = "0.8.5", features = ["small_rng"] }
+rand_chacha = "0.3.1"
+rand_distr = "0.4.3"
+rand_pcg = "0.3.1"
+rand_seeder = "0.2.3"
+```