Set the text for the release body to reference license (#3610)

Make reference to our license in the text description of our releases.

.github/workflows/build-release.yml

@@ -92,6 +92,12 @@ jobs:
         with:
           draft: false
           prerelease: true
+          body: |
+            Thank you for helping test this pre-release of Positron!
+
+            Installers can be found under the **Assets** section below. Select the `.dmg` for Mac (Universal), `.exe` for Windows x64 (System), or `.deb` for Debian-based Linux (Ubuntu).
+
+            Please review [Positron's license agreement](https://github.com/posit-dev/positron?tab=License-1-ov-file#readme). Your acceptance of this license agreement is required as a condition to proceeding with your download or use of the software.
           release_name: ${{ needs.version_string.outputs.short_version }}
           tag_name: ${{ needs.version_string.outputs.short_version }}