add changeset

Author: acao

.changeset/shiny-colts-tie.md

@@ -0,0 +1,9 @@
+---
+"@graphiql/plugin-code-exporter": patch
+"@graphiql/plugin-explorer": patch
+"@graphiql/plugin-utils": patch
+"@graphiql/react": patch
+"graphiql": patch
+---
+
+introduce `@graphiql/plugin-utils` to simplify tooling & provide plugin development documentation