Update install deps in README

README.md

@@ -140,6 +140,10 @@ A few basic steps are needed to get set up:
    3. Use the command `rustup show` to get information about the Rust installation. You should see that the active toolchain is the stable version. 
    4. Run  `rustc --version` to check the installation and version of rust.
       - Updates can be performed using` rustup update` .
+   5. Install build dependancies (Arch packages are listed here, your distribution will
+	  likely be similar):
+	  - `clang`: required by RocksDB.
+	  - `protobuf`: required for protobuf serialization (gRPC).
    5. Navigate to the working directory.
    6. Run the test by using command `cargo test --all` . By running, it will pass all the required test cases. If you are doing it for the first time, then you can grab a coffee meantime. Usually, it takes time to build, compile and pass all test cases. If there is no error then, it means everything is working properly and it's time to get hand's dirty. In case, if there is an error, then please raise the [issue](https://github.com/sigp/lighthouse/issues).  We will help you.
    7. As an alternative to, or instead of the above step, you may also run benchmarks by using the command `cargo bench --all`