docs: update README.md with info for community

...and move information about our release process into a separate
`Release.md` file.

Author: cwillisf

README.md

@@ -1,11 +1,51 @@
-# scratch-editor
+# scratch-editor: The Scratch Editor Monorepo
 
-Scratch editor mono-repo
+If you'd like to use Scratch, please visit the [Scratch website](https://scratch.mit.edu/). You can build your own
+Scratch project by pressing "Create" on that website or by visiting <https://scratch.mit.edu/projects/editor/>.
 
-## Release monorepo
+This is a source code repository for the packages that make up the Scratch editor and a few additional support
+packages. Use this if you'd like to learn about how the Scratch editor works or to contribute to its development.
 
-1. On GitHub, navigate to the main page of the [repository](https://github.com/scratchfoundation/scratch-editor/tree/develop).
-2. To the right of the list of files, click **Releases**, click **Draft a new release**.
-3. To create a tag for the release, select the **Choose a tag** dropdown menu, type a version number for your release, then click **Create new tag**. The tag of the release is used to determine and update package versions.
-4. In the **Describe this release** field, type a description for your release. If you @mention anyone in the description, the published release will include a Contributors section with an avatar list of all the mentioned users. Alternatively, you can automatically generate your release notes by clicking **Generate release notes**. This provides a list with the **Pull Requests** included in the release and their creators.
-5. Clicking **Publish release** triggers the publishing workflow that will publish the monorepo packages to **NPM**
+## What's in this repository?
+
+The `packages` directory in this repository contains:
+
+- `scratch-gui` provides the buttons, menus, and other elements that you interact with when creating and editing a
+  project. It's also the "glue" that brings most of the other modules together at runtime.
+- `scratch-render` draws backdrops, sprites, and clones on the stage.
+- `scratch-svg-renderer` processes SVG (vector) images for use with Scratch projects.
+- `scratch-vm` is the virtual machine that runs Scratch projects.
+
+_Please add to this list as more packages are migrated to the monorepo._
+
+Each package has its own `README.md` file with more information about that package.
+
+## Monorepo migration
+
+### What's going on?
+
+We're migrating the Scratch editor packages into this monorepo. This will allow us to manage all the packages that
+make up the Scratch editor in one place, making  it easier to manage dependencies and make changes that affect
+multiple packages.
+
+### Why are there only a few packages in this repo?
+
+We're migrating packages in stages. The current plan, which is subject to change, has us migrating repositories in
+four batches. We plan to complete the migration within 2025.
+
+### What will happen to the existing repositories?
+
+The existing repositories will be archived and made read-only. Those repositories contain valuable work and
+information, including but not limited to issues and pull requests. We plan to keep that information available for
+reference, and to selectively migrate it to this new repository.
+
+## Thank you!
+
+Scratch would not be what it is today without help from the global community of Scratchers and open-source
+contributors. Thank you for your contributions and support. _[Scratch on!](https://scratch.mit.edu/projects/65347738/fullscreen/)_
+
+## Donate
+
+We provide [Scratch](https://scratch.mit.edu) free of charge, and want to keep it that way! Please consider making a
+[donation](https://secure.donationpay.org/scratchfoundation/) to support our continued engineering, design, community,
+and resource development efforts. Donations of any size are appreciated. Thank you!

Release.md

@@ -0,0 +1,17 @@
+# Release process
+
+_For maintainers of this monorepo._
+
+All packages in this monorepo will be published to NPM when a new release is created. They'll all share the same
+version number. To create a new release:
+
+1. Select "Draft a new release" from [the repository's "Releases"
+   tab](https://github.com/scratchfoundation/scratch-editor/releases) or "Create a new release" from [the main page of
+   the repository](https://github.com/scratchfoundation/scratch-editor/).
+2. To create a tag for the release, select the **Choose a tag** dropdown menu, type a version number for your release,
+   then click **Create new tag**. The tag of the release is used to determine and update package versions.
+3. In the **Describe this release** field, type a description for your release. If you @mention anyone in the
+   description, the published release will include a Contributors section with an avatar list of all the mentioned
+   users. Alternatively, you can automatically generate your release notes by clicking **Generate release notes**.
+   This provides a list with the **Pull Requests** included in the release and their creators.
+4. Clicking **Publish release** triggers the publishing workflow that will publish the monorepo packages to NPM.