improve README

tests/ulm/erc20/rust/README.md

@@ -5,4 +5,19 @@ This directory contains a Rust implementation of an ERC20 contract that is compi
 As is the case with many chains that use Wasm contracts, we compile this Rust project as a library;
 that way, functions referenced in external libraries become host functions which can be provided via Wasm module imports.
 
-In order to reduce the 
+In order to reduce the size of the compiled Wasm library, we referred to this guide:
+
+https://github.com/johnthagen/min-sized-rust
+
+To build the contract with all of the size minimization options, first, ensure that a recent build of the Rust compiler is installed with the Wasm32 target, which can be done with:
+
+```sh
+rustup install nightly
+rustup target add wasm32-unknown-unknown --toolchain nightly
+```
+
+Then run the build script as follows:
+
+```sh
+build.sh
+```

tests/ulm/erc20/rust/build.sh

@@ -1,6 +1,7 @@
 #!/bin/bash
 LOC_FLAG="-Zlocation-detail=none" # removes debugging info from binary
 FMT_FLAG="-Zfmt-debug=none"       # removes formatter code from binary
+# the last two lines build stdlib for target with minimal panic handling and optimized for size
 RUSTFLAGS="$LOC_FLAG $FMT_FLAG" cargo +nightly build --release --target wasm32-unknown-unknown \
--Z build-std=std,panic_abort \
+-Z build-std=std,panic_abort                                                                   \
 -Z build-std-features="optimize_for_size,panic_immediate_abort"