Update CONTRIBUTING.md
Add example on how to build a small set of features to prevent filling up the memory
@@ -34,7 +34,7 @@ To run only the in-crate unit tests, which don't call out to AWS, include the `-
For more verbose test output, you can run `cargo test --verbose --features FEATURE -- --nocapture`.
-**Warning**: When building or testing with `--features all` the build/test can require upwards of 5 GB of memory. Make sure you have memory available before building/testing or limit the number of features you build/test at once.
+**Warning**: When building or testing with `--features all` the build/test can require upwards of 5 GB of memory. You can limit the number of features to build at once to prevent running out of memory. That can be achieved using the `--features` flag, e.g. `cargo build --features "packagea packageb"`. See [README](README.md) for a table of available services and their Cargo feature names.
### Rust code generation from boto core service definitions:
