chore(hack): allow for revisions count

It is possible now to define how many revisions back the script should
investigate. By default it is 5.

To change it to 3:

```
./hack/generate-release-notes.sh 3
```

hack/generate-release-notes.sh

@@ -20,21 +20,22 @@
 
 set -e
 
-if [ "$#" -ne 0 ]; then
-    echo "Illegal number of parameters, provided $#, required: 0"
+if [ "$#" -gt 1 ]; then
+    echo "Illegal number of parameters, provided $#, required: 0 or 1"
     echo
     echo "Usage:"
     echo "    ${0}"
+    echo "    ${0} 3"
     exit 1
 fi
 
 KUBE_CONTEXT="${KUBE_CONTEXT:-aws-prod}"
-REVISIONS=5
+REVISIONS="${1:-5}"
 
 export TZ=":UTC"
 
 echo "---- Release history ----"
-history=$(helm --kube-context "${KUBE_CONTEXT}" -n sbomer--runtime-int history --max ${REVISIONS} sbomer 2>/dev/null)
+history=$(helm --kube-context "${KUBE_CONTEXT}" -n sbomer--runtime-int history --max ${REVISIONS} sbomer)
 
 echo "$history"