Update Julia advice to include precompilation

README.md

@@ -47,10 +47,11 @@ then instructions for [mac](https://julialang.org/downloads/platform/#macos)
 and [linux](https://julialang.org/downloads/platform/#linux_and_freebsd).
 (Don't use the `conda-forge` version; it doesn't seem to work properly.)
 Then, at the command line,
-install the `Optim` and `SpecialFunctions` packages via:
+install and precompile the `Optim` and `SpecialFunctions`
+packages via:
 
 ```bash
-julia -e 'import Pkg; Pkg.add("Optim"); Pkg.add("SpecialFunctions")'
+julia -e 'using Pkg; pkg"add Optim; add SpecialFunctions; precompile;"'
 ```
 
 For python, you need to have Python 3, numpy, sympy, and pandas installed.