Update content-style-guide.md

Author: hubwriter

contributing/content-style-guide.md

@@ -389,6 +389,8 @@ Always use "GitHub Codespaces" (`{% data variables.product.prodname_github_codes
 
 Always use "dev container" (or, where clarification is needed, its longer form "development container") and not "devcontainer" (one word), except in file/path names. The single word could form could be considered a brand, which we want to avoid, and we also want to be consistent with the two-word form used in [the Visual Studio Code documentation](https://code.visualstudio.com/docs/remote/create-dev-container#_path-to-creating-a-dev-container).
 
+Use "development container configuration files" to refer to all of the files in the `.devcontainer` directory (plus the `.devcontainer.json` if that's being used rather than `devcontainer.json` in the `.devcontainer` directory). Don't refer to these as "development container files" or "devcontainer files" to avoid this being taken as referring to `devcontainer.json` files. "Development container configuration files" refers to all of the files that can be used to configure a dev container, including `Dockerfile` and `docker-compose.yml` files. Don't use "the development container configuration file" (singular) when referring specifically to a `devcontainer.json` file. Instead refer to this file by its name.
+
 ## Punctuation
 
 Follow standard American English punctuation rules. For more guidance, see “[Punctuation](https://brand.github.com/content/grammar#punctuation)” in GitHub’s Brand Guide and “[Punctuation](https://docs.microsoft.com/style-guide/punctuation)” in the Microsoft Style Guide.