Update readme

Author: Ben Wyatt

README.md

@@ -1 +1,14 @@
-java_rs
+This is a project for working with Java from Rust code. Currently includes read-only classfile browsing from inside Rust code as well as a GUI. Hopefully one day will include a JVM.
+
+# Build
+
+Clone the repository and open up the base directory in a shell of your choice and make sure Rust is installed. Then run a command:
+## Build only
+
+`cargo build --release`
+
+## Run browser GUI
+
+`cargo run --release -p class_browser`
+
+Binaries are found in `./target/release/`