Notes from first-time user

After chatting with @favyen2 , I had a look at the repo and started playing around. Here are some notes in case they prove useful to update documentation.

## Notes

### List of remotes

There are 3 Remotes with downloadable data:
- https://ai2-public-datasets.s3.amazonaws.com/satlas/ which is an AWS S3 bucket
- https://huggingface.co/allenai/satlas-pretrain which is HuggingFace (relates to #15)
- https://pub-956f3eb0f5974f37b9228e0a62f449bf.r2.dev/ which is a Cloudflare R2 bucket ([ref](https://developers.cloudflare.com/r2/)) hosted on GCP (found via `whois pub-956f3eb0f5974f37b9228e0a62f449bf.r2.dev`)

### Interacting with the S3 bucket

When deciding what to download, I found the need to know "a priori" the size of what I was going to download. Partly to make sure I download the right thing, and partly to inform my system choice (i.e. do I work from my mac or from a cloud box)
To understand what you have published at a glance (training datasets & model weights) as well as their respective sizes, I ran:

```sh
aws s3 ls s3://ai2-public-datasets/satlas/ --human-readable
```

### Interacting with the R2 bucket

Just like for the S3 bucket, I wanted to list files present in the bucket with their size (dataset & model weights) especially as this Remote is apparently used for the fine-tuning tasks that interest me.

R2 is supposed to expose a S3 API ([ref](https://developers.cloudflare.com/r2/examples/aws/aws-cli/))
Unfortunately, I was unable to get anywhere and I don't get a helpful error message either, so I am stuck:
```sh
→ aws s3api list-buckets --endpoint-url https://pub-956f3eb0f5974f37b9228e0a62f449bf.r2.dev/

An error occurred () when calling the ListBuckets operation:
→ aws s3api list-objects-v2 --endpoint-url https://pub-956f3eb0f5974f37b9228e0a62f449bf.r2.dev --bucket satlas_explorer_datasets

An error occurred () when calling the ListObjectsV2 operation:
```

### Minor gitignore tweak
Because the docs expect me to populate a `models/` and a `vis/` folder, but those are not tracked in git, I ended up adding those 2 folders to my local gitignore in `.git/info/exclude` so that they don't get tracked while not touching the committed `.gitignore`

### Solar Farm model links?

According to the docs, `models/solar_farm/best.pth` is one of the artifacts present in the R2 bucket (https://pub-956f3eb0f5974f37b9228e0a62f449bf.r2.dev/satlas_explorer_datasets/satlas_explorer_datasets_2023-07-24.tar).
Is there a way to download only that file directly and not the rest of the archive?