Update coverage target and README (#104)

- Updated coverage section of the README.
- Updated coverage target in Makefile to generate html report

Makefile

@@ -24,6 +24,7 @@ coverage:
 	$(MAKE) start-anvil > /dev/null &
 	sleep 4 # needed to wait for anvil setup to finish
 	cargo llvm-cov --lcov --output-path lcov.info --ignore-filename-regex='fireblocks/' --workspace
+	cargo llvm-cov report --html --ignore-filename-regex='fireblocks/'
 	docker stop anvil
 
 deps:

README.md

@@ -68,20 +68,17 @@ Here's how to generate test coverage reports:
 
 Install llvm tools:
 ```
-rustup component add llvm-tools-preview
+make deps
 ```
 
 Run the tests with coverage instrumentations:
 ```
-cargo clean && mkdir -p coverage/ && rm -r coverage/*
-CARGO_INCREMENTAL=0 RUSTFLAGS='-Cinstrument-coverage' LLVM_PROFILE_FILE='coverage/cargo-test-%p-%m.profraw' cargo test --no-fail-fast
+make coverage
 ```
 
-Install coverage report tool and run it:
+Open the coverage html report in a web browser:
 ```
-cargo install grcov
-grcov . --binary-path ./target/debug/deps/ -s . -t html --branch --ignore-not-existing --ignore '../*' --ignore "/*" -o target/coverage/
-
+open target/llvm-cov/html/index.html
 ```
 
 ## Supported Rust Version