feat(copier): adds a better readme where the sample.env was

Author: Matt-Carre

src/copier_template/src/README.md

@@ -0,0 +1,9 @@
+# Setting up a development environment
+1. Build the dev container
+2. run "uv lock" to generate the uv.lock file
+3. Create .env in this folder (with the path src/.env) containing the following variables:
+HOST=https://argo-workflows.workflows.diamond.ac.uk/ (to submit to the production repo)
+IMAGE= (usually python 3.10)
+TOKEN=
+NAMESPACE= (the cluster you wish to run the templates on)
+AUTH=