add initial marketplace docs

marketplace.md

@@ -0,0 +1,48 @@
+Marketplace
+===========
+
+## How to connect a marketplace app to a Pegasus project
+
+Follow these steps to connect a marketplace app to a Pegasus project.
+We'll do this for [scriv], but the process should be the same for other apps built on Pegasus.
+
+First, [follow the getting started guide](https://www.saaspegasus.com/store/product/scriv/get-started/)
+to clone the repository and set up your own fork.
+
+Next, create new Pegasus project for your app from [the projects page](https://www.saaspegasus.com/projects/).
+**You should choose the same config choices as the marketplace app**,
+which you can find in the `pegasus-config.yaml` file in the repository root.
+
+You can also refer to [this screenshot](/images/marketplace/scriv-pegasus-config.png) for how the configuration
+should look as of September, 2024.
+
+Next, connect your Pegasus project to your Github repository:
+
+1. From the project page, select "Get Code".
+2. On the "Push to Github" tab, click "Add a repo".
+3. Set the owner and name to the fork you created above.
+4. Click "Add Repo".
+
+You will be prompted to authenticate with Github.
+If you haven't already, you should set that up according to [the Github guide](https://docs.saaspegasus.com/github/#connecting-your-account).
+
+After connecting your Github, you will be prompted to enter a commit ID according to the last Pegasus commit
+in the repository. You should enter the commit ID of the most recent Pegasus update, which you can
+get from the table below:
+
+| Codebase            | Commit ID                                  | Last Updated |
+|---------------------|--------------------------------------------|--------------|
+| Scriv               | `2e6a656778a55e115e236680e37fe2773dcc3bd4` | Sep 4, 2024  |
+| Translation Creator | `60595de93e05161de3cd2a25678da7ddd9ac0709` | Sep 4, 2024  |
+
+Enter the commit ID and click "Set Commit ID".
+
+Now you should be able to click "Submit Pull Request" and your Pegasus project will sync with your marketplace codebase.
+Once this completes you should have a Github pull request with a small number of changes.
+You may need to resolve conflicts on this pull request (when in doubt, accept the `main` branch changes).
+Once you have resolved all conflicts, merge the pull request.
+
+Your marketplace is now connected to your Pegasus project!
+You can change settings, upgrade, and submit pull requests from Pegasus and they will go to your marketplace app repo.
+
+If you have any questions or issues with this process, [get in touch via the support channels](https://www.saaspegasus.com/support/).