updated docs

README.md

@@ -4,15 +4,39 @@
 
 ### Spack
 
+This assumes that you have spack installed and sourced. If not, you can install
+it using the following commands
+
+```bash shell
+$ git clone -c feature.manyFiles=true --depth=2 https://github.com/spack/spack.git
+
+# For bash/zsh/sh
+$ . spack/share/spack/setup-env.sh
+
+# For tcsh/csh
+$ source spack/share/spack/setup-env.csh
+
+# For fish
+$ . spack/share/spack/setup-env.fish
+```
+
+Now in the root directory of this repository, you can load the spack environment
+that contains the packages needed to build the project.
+
 ```bash shell
+# 1. Activate the local environment
 $ spack env activate ./spack-env
+
+# 2. Compile and install the packages listed in the environment
 $ spack install
+
+# optional?? it looks like cmake can still find the packages just by loding the environment using pkg-config
 $ spack load openblas openmpi petsc
 ```
 
 ### CMake
 
-To build main from main.c
+To build `main` from `main.c`
 
 ```bash shell
 $ rm -rf build