Merge pull request #146 from jacobweinstock/grub2disk-image

Update readme:

## Description

<!--- Please describe what this PR is going to change -->
The readme example had a lot of mounts that weren't needed and broke the Action.

## Why is this needed

<!--- Link to issue you have raised -->

Fixes: #

## How Has This Been Tested?
<!--- Please describe in detail how you tested your changes. -->
<!--- Include details of your testing environment, and the tests you ran to -->
<!--- see how your change affects other areas of the code, etc. -->


## How are existing users impacted? What migration steps/scripts do we need?

<!--- Fixes a bug, unblocks installation, removes a component of the stack etc -->
<!--- Requires a DB migration script, etc. -->


## Checklist:

I have:

- [ ] updated the documentation and/or roadmap (if required)
- [ ] added unit or e2e tests
- [ ] provided instructions on how to upgrade

Author: jacobweinstock

grub2disk/README.md

@@ -13,18 +13,7 @@ tasks:
     worker: "{{.device_1}}"
     volumes:
       - /dev:/dev
-      - /proc:/proc
       - /sys:/sys
-      - /mnt:/mnt
-      - /statedir:/statedir
-      - /etc:/etc
-      - /bin:/bin
-      - /sbin:/sbin
-      - /var:/var
-      - /usr:/usr
-      - /lib:/lib
-      - /tmp:/tmp
-      - /boot:/boot
     actions:
       - name: "grub_2_disk"
         image: quay.io/tinkerbell/actions/grub2disk:latest