Fix Sharpy build steps in README.md (#7)

Update README.md

Author: AllanZyne

Diff for: README.md

@@ -9,12 +9,11 @@ Parallel and distributed execution currently is MPI/CSP-like. In a later version
 
 ## Setting up build environment
 
-Install MLIR/LLVM and Intel® Extension for MLIR (IMEX, see https://github.com/intel/mlir-extensions).
+Install MLIR/LLVM and Intel® Extension for MLIR (IMEX, see https://github.com/intel/mlir-extensions). Make sure you use `-DLLVM_ENABLE_RTTI=ON` when configuring LLVM and use build target `all`.
 
 ```bash
 git clone --recurse-submodules https://github.com/IntelPython/sharded-array-for-python
 cd sharded-array-for-python
-git checkout jit
 conda create --file conda-env.txt --name sharpy
 conda activate sharpy
 export MPIROOT=$CONDA_PREFIX