document how to reuse Grapes cache

groovy/content.md

@@ -13,3 +13,12 @@
 ## Running a Groovy script
 
 `docker run --rm -v "$PWD":/scripts -w /scripts --name groovy groovy:alpine groovy <script> <script-args>`
+
+## Reusing the Grapes cache
+
+The local Grapes cache can be reused across containers by creating a volume and mounting it in */home/groovy/.groovy/grapes*.
+
+```console
+docker volume create --name grapes-cache
+docker run -it -v grapes-cache:/home/groovy/.groovy/grapes groovy:alpine
+```