Updated s3 directions, noted other cloud providers, added warning

brief description of changes

I updated the S3 example to reference the current version of the Python Boto3 library for interfacing with S3.

I also made a few edits to discuss other cloud storage providers so it doesn't read quite like an AWS advertisement. Please let me know if you think these changes properly reflect the current reality.

issues addressed

(https://github.com/archesproject/arches-docs/issues/323)

further comments

This change will need to applied to almost all branches.

This box must be checked

[x] the PR branch was originally made from the base branch

This box should be checked

[x] after these changes the docs build locally without error

This box should only be checked you intend to follow through on it (we can do it on our end too)

[x] I will cherry-pick all commits in this PR into other branches that should have them after this PR is merged

archesproject / arches-docs