update README

## Build

For the default build, run the following. `LLVM 14` will be used by default.

`reverser` currently runs on `LLVM 14`. It can be installed with

```

apt install llvm-14 zlib1g-dev

```

To build `reverser`, run

```

cmake -B build

cd build

make

cmake --build build

```

To build with a specific LLVM version, run `cmake -DLLVM_VERSION=version -B build`. The implementation is currently being developed on LLVM 14. 

To build with a specific LLVM version, run `cmake -DLLVM_VERSION=version -B build`, but we give no guarantees for other versions than 14.

Optionally, use the attached dockerfile with commands

```

docker build -t reverser .

docker run --rm -it reverser

```

## Run

```

./build/reverser --input input_file.ll --output output_file.ll

./build/reverser -o output_file.ll <options> input_file.ll

```

Use `--bc` for output as a binary file (.bc).