Spacemacs-on-Joule.md

@@ -24,6 +24,7 @@ There is a compiled version of Emacs under `/nfs/home/public`:
 ```
 > module load gnu/8.4.0
 > source /nfs/home/public/mmeredith/spack/share/spack/setup-env.sh
+> spack compiler add   # Creates ~/.spack/compilers.yaml; only necessary to run once
 > spack load emacs
 > emacs --version  # Should be GNU Emacs 26.3
 ```