Add Documentation for Installing Extension from VSIX in Dev Container

[autrk]

I recently discovered this promising project and have been using the extension in a VSCode workspace within a dev container in WSL on Windows. Since the extension is not yet available on the marketplace, I installed it in my dev container using an undocumented feature. Instead of referencing the extension's ID, you simply provide the path to the VSIX file in the dev container.

I would like to suggest adding a chapter to the README.md that explains how this works. Essentially, you need to make the VSIX file available in the dev container via a volume and specify the path to the extension in the devcontainer.json file instead of the extension ID.

Here is a summary of the steps:

• Place the VSIX file in a directory that is accessible to the dev container and mout this folder into the devcontainer, e.g. in your compose file:
  # Unpublished extensions - ./extensions:/extensions
• In the devcontainer.json file, specify the path to the VSIX file instead of the extension ID:
  "extensions": [ "/extensions/cornifer-0.30.0.vsix" ]

This additional documentation would be very helpful for others who want to use the extension in a similar setup. I would like to contribute the documentation via a pull request.

[RVR06]

Hi Christian,
Thank you for your feedback.

Publishing Cornifer to marketplace is planned, so it will ease the .devcontainer setup.
I was not aware of this undocumented feature, once again thanks for sharing.

Contributions are welcome so feel free to craft a PR to amend documentation accordingly.

[autrk]

I have created a pull request #7