Add install script for shells

README.md

@@ -16,7 +16,6 @@
 - from the repo's root directory, run `./box_setup`
 
 ### todo items
-- review primeagen's runs dir
 - nvim config
 - consider: optional vim config as a backup?
 - decide on and implement approach for languages and versioning

installs_and_builds/s03_shells

@@ -0,0 +1,3 @@
+#!/bin/zsh
+
+${=BOX_SETUP_INSTALL_COMMAND} zsh