Update README.md

README.md

@@ -38,7 +38,7 @@ If you're interested in submitting a PR, it would be a good idea to set up your
 * [foodcritic](http://www.foodcritic.io/) for Chef script linting
 
 ### Tooling
-New contributions should consist entirely of Python(2, soon to be 3) code or Terraform scripts. No new shell script code will be accepted. If you want to add a new optional feature (rather than simply bugfix) please chat with the maintainers in Slack before starting, and take a look at the `feature-extensions` subdirectory for an example of how we currently structure such things.
+New contributions should consist entirely of Python(2, soon to be 3) code or Terraform scripts. No new shell script code will be accepted, we have too much of it and it's not particularly maintainable. If you want to add a new optional feature (rather than simply bugfix) please chat with the maintainers in Slack before starting, and take a look at the `feature-extensions` subdirectory for an example of how we currently structure such things.
 
 ### Branching/release flow
 1. Breaking/nontrivial features first go into named feature branches cut from `develop`