chore: add root changelog

CHANGELOG.md

@@ -0,0 +1,23 @@
+# Changelog
+
+This repository is a [monorepo](https://en.wikipedia.org/wiki/Monorepo). You will find the changelogs here:
+
+- [gridsome](./gridsome/CHANGELOG.md)
+- [@gridsome/cli](./packages/cli/CHANGELOG.md)
+- [@gridsome/plugin-critical](./packages/plugin-critical/CHANGELOG.md)
+- [@gridsome/plugin-google-analytics](./packages/plugin-google-analytics/CHANGELOG.md)
+- [@gridsome/plugin-sitemap](./packages/plugin-sitemap/CHANGELOG.md)
+- [@gridsome/remark-prismjs](./packages/remark-prismjs/CHANGELOG.md)
+- [@gridsome/source-airtable](./packages/source-airtable/CHANGELOG.md)
+- [@gridsome/source-contentful](./packages/source-contentful/CHANGELOG.md)
+- [@gridsome/source-datocms](./packages/source-datocms/CHANGELOG.md)
+- [@gridsome/source-drupal](./packages/source-drupal/CHANGELOG.md)
+- [@gridsome/source-faker](./packages/source-faker/CHANGELOG.md)
+- [@gridsome/source-filesystem](./packages/source-filesystem/CHANGELOG.md)
+- [@gridsome/source-ghost](./packages/source-ghost/CHANGELOG.md)
+- [@gridsome/source-graphql](./packages/source-graphql/CHANGELOG.md)
+- [@gridsome/source-wordpress](./packages/source-wordpress/CHANGELOG.md)
+- [@gridsome/transformer-csv](./packages/transformer-csv/CHANGELOG.md)
+- [@gridsome/transformer-json](./packages/transformer-json/CHANGELOG.md)
+- [@gridsome/transformer-remark](./packages/transformer-remark/CHANGELOG.md)
+- [@gridsome/transformer-yaml](./packages/transformer-yaml/CHANGELOG.md)