Add cleanup instructions to release-notes generation

Author: msau42

SIDECAR_RELEASE_PROCESS.md

@@ -54,14 +54,19 @@ naming convention `<hostpath-deployment-version>-on-<kubernetes-version>`.
   generator](https://github.com/kubernetes/release/tree/master/cmd/release-notes)
 1. Generate release notes for the release. Replace arguments with the relevant
   information.
+    * Clean up old cached information (also needed if you are generating release
+      notes for multiple repos)
+      ```bash
+      rm -rf /tmp/k8s-repo
+      ```
     * For new minor releases on master:
-        ```
+        ```bash
         GITHUB_TOKEN=<token> release-notes --discover=mergebase-to-latest
         --github-org=kubernetes-csi --github-repo=external-provisioner
         --required-author="" --output out.md
         ```
     * For new patch releases on a release branch:
-        ```
+        ```bash
         GITHUB_TOKEN=<token> release-notes --discover=patch-to-latest --branch=release-1.1
         --github-org=kubernetes-csi --github-repo=external-provisioner
         --required-author="" --output out.md