[Bug] "Getting Started" guide trying to write on SquashFS

[Silvanoc]

Describe the bug

The Getting Started guide is using a SquashFS image as root-fs, but then tries to write on it to update the resolv.conf.

To Reproduce

Two options:

• Follow the Getting Started guide and see the mentioned modification of resolv.conf fail.
• Simply analyze the guide to realize the inconsistency

Expected behaviour

Two options:

• Read-only guide: SquashFS is used and no resolv.conf modification is done
• Writable guide: a writable Ext4 FS is used

Environment

Additional context

Checks

• Have you searched the Firecracker Issues database for similar problems?
• Have you read the existing relevant Firecracker documentation?
• Are you certain the bug being reported is a Firecracker issue?

[roypat]

Hey @Silvanoc,
thanks for reporting this! We also noticed this yesterday, and posted a fix in #4928