Add more docs to explain details and fix #99

Fixes #99 (closed) where the extra env variables exposed via recipe_append.yaml are no longer exposed.

bob/devtools/data/gitlab-ci/single-package.yaml

@@ -54,6 +54,8 @@ stages:
   tags:
     - bob
     - docker
+  # make sure we use the same image as conda-forge:
+  # https://github.com/conda-forge/conda-forge-pinning-feedstock/blob/main/recipe/conda_build_config.yaml
   image: quay.io/condaforge/linux-anvil-cos7-x86_64
   artifacts:
     paths: