Readme improvements

[AngelOnFira]

I'm trying to follow the readme, but I'm running into lots of issues understanding it. If I make it through, I'll try to make a PR with some clarity changes, but I wanted to note some issues that I was wondering about upfront.

1. In the container network config section, I tried figuring out how to install both repos, but couldn't make it work.
2. It would be nice to know what is the "minimum to install" from the requirements, vs "nice to have" (if there are any that aren't required, I haven't made it through).
3. I tried glancing over the rootfs and image section, but don't really understand why it's needed. This might just be my lack of Firecracker understanding though.

I'm also wondering, why do all the task driver options start with an uppercase letter? Makes them quite unpleasant to have in a Nomad file while other options are lowercase afaik.

Anyways, we'll see how far I get, but some insight might be nice :)

[cneira]

@AngelOnFira how did it go?. were you able to spin up a firecracker task on nomad?. Let me know which steps were not clear. here is step by step guide by an user https://kruzenshtern.org/run-a-firecracker-on-nomad/