Update README.md: Add info about data persistency

.devcontainer/README.md

@@ -22,6 +22,19 @@ For use with Github Codespaces, please follow the instruction at
 For local/'remote host' usage with VS Code, please follow the instructions at
 [Developing inside a Container](https://code.visualstudio.com/docs/devcontainers/containers).
 
+### Persistence
+
+Data in the following locations is persisted:
+
+1. The user's home directory (`/home/vscode`)[^1]
+2. The Dev Container's workspace (`/workspaces`)
+
+[^1]: Alternatively for the root user (`/root`). Use with Docker/Podman in
+*rootless mode*.
+
+This is accomplished either via a *volume* or *bind mount* and is
+preconfigured.
+
 ## Install pandoc
 
 ### Using cabal