Add new content to section Contribution in README.md (#44)

Author: NobodyXu

README.md

@@ -28,3 +28,31 @@ at your option.
 Unless you explicitly state otherwise, any contribution intentionally submitted
 for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
 dual licensed as above, without any additional terms or conditions.
+
+### Run integration tests
+
+Requires `docker` and [`cargo-hack`].
+
+Check [getting Docker guide](https://docs.docker.com/get-docker/) on how to install docker,
+and use `cargo install cargo-hack` to install [`cargo-hack`].
+
+```
+./run_ci_tests.sh
+```
+
+It will create a container which runs sshd, setup ssh-agent, and environment variables
+that are required to run the integration tests.
+
+It will also test different combination of feature flags to ensure they all compile without error.
+
+[`cargo-hack`]: https://github.com/taiki-e/cargo-hack
+
+### Build documentation
+
+Requires nightly cargo.
+
+To install nightly cargo, run `rustup toolchain install nightly`.
+
+```
+./build_doc.sh
+```