feat(volume-mount): mount docker volumes as input (#797)

Co-authored-by: Michael Kriese <michael.kriese@visualon.de>

README.md

@@ -13,6 +13,7 @@ GitHub Action to run Renovate self-hosted.
   - [`configurationFile`](#configurationfile)
   - [`docker-cmd-file`](#docker-cmd-file)
   - [`docker-user`](#docker-user)
+  - [`docker-volumes`](#docker-volumes)
   - [`env-regex`](#env-regex)
   - [`mount-docker-socket`](#mount-docker-socket)
   - [`token`](#token)
@@ -114,6 +115,31 @@ Specify a user (or user-id) to run docker command.
 You can use it with [`docker-cmd-file`](#docker-cmd-file) in order to start the
 image as root, do some customization and switch back to a unprivileged user.
 
+### `docker-volumes`
+
+Specify volume mounts. Defaults to `/tmp:/tmp`.
+The volume mounts are separated through `;`.
+
+This sample will mount `/tmp:/tmp`, `/home:/home` and `/foo:/bar`.
+
+```yml
+....
+jobs:
+  renovate:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3.5.3
+      - name: Self-hosted Renovate
+        uses: renovatebot/github-action@v39.1.3
+        with:
+          token: ${{ secrets.RENOVATE_TOKEN }}
+          docker-volumes: |
+            /tmp:/tmp ;
+            /home:/home ;
+            /foo:/bar
+```
+
 ### `env-regex`
 
 Allows to configure the regex to define which environment variables are passed to the renovate container.