Clean up installation instructions

README.md

@@ -42,13 +42,16 @@ then instructions for [mac](https://julialang.org/downloads/platform/#macos)
 and [linux](https://julialang.org/downloads/platform/#linux_and_freebsd).
 Then, at the command line,
 install the `Optim` and `SpecialFunctions` packages via:
-`julia -e 'import Pkg; Pkg.add("Optim"); Pkg.add("SpecialFunctions")'`.
+
+```bash
+julia -e 'import Pkg; Pkg.add("Optim"); Pkg.add("SpecialFunctions")'
+```
 
 For python, you need to have Python 3, numpy, sympy, and pandas installed.
 
 You can install this package from PyPI with:
 
-```
+```bash
 pip install pysr
 ```