Upgrade carbonplan version and update aws upgrade docs

[GeorgianaElena]

For #3224

[sgibson91]

LGTM! I've left some comments trying to clean up the language a bit, but I think this is a complex topic so if I've misunderstood anything feel free to ignore it.

[GeorgianaElena]

@sgibson91 and @consideRatio, many thanks for your feedback. I have added a bunch of commits this morning that I hope made the info a bit more clear.

Check it out at https://2i2c-pilot-hubs--3420.org.readthedocs.build/howto/upgrade-cluster/aws/ and let me know what you think

[consideRatio]

I think the commit part is complicated because we don't version control it, and I don't think we should either. I think it simply doesn't get easier than the somewhat tricky procedure that requires attention to make sure to keep track of what is being applied - it will always be the yaml file as written to disk. If you introduce work on committing, it adds additional steps and complexity, especially since its not a version controlled file.

Due to this, I'd favor the removal of this optional step and nesting the important admonition under the third step.

---

Here "the config file" is mentioned to be the .jsonnet file specifically. I think this should be left not explicit, letting the reader either update the .yaml file, or the jsonnet file + generate like done in the step below. Compare:

---

With three minor version upgradable at the time, I think we should lean on the reduced complexity we can arrive at and assume we never need to upgrade more then three versions at the time.

This doesn't belong any more i think, after we upgraded the control plan version 1-3 times, we should simply have stayed at there going onwards. This change was also the only change to commit btw.

[consideRatio]

Thanks for working on this @GeorgianaElena!! I figure we can merge, and if needed we can do another iteration at some later time. Its really tricky to document this procedure I think!

[GeorgianaElena]

Thanks @consideRatio. I've added one more commit and going for a merge now.