Devcontainer doesn't open workspace when configuration file is in a sub-folder

If you have a folder structure for the `.devcontainer` configuration files where they are subdivided to accommodate multiple devcontainers (e.g. `academic_markdown` and `python` under `.devcontainer`), `academic_markdown` doesn't properly mount the workspace folder. 

One clue might be that trying to list the files of the folder currently opened in the container gives 'no permissions'. 