S3 Storage Configuration documentation requires improvements

[jouvin]

I tried to use the S3 Storage Configuration official documentation and my experience is that is doesn't allow to get a working S3 RSE. Among the issues experienced (thanks for the help on Mattermost!), I identified:

• lfn2pfn_algorithm must be defined at creation time (not sure how) as it cannot be changed once it is set (according to https://rucio.github.io/documentation/operator/configuration_parameters/#rse-settings) and in fact is refused by rucio rse update (or its rucio-admin equivalent).
• s3_url_style must be set to path, except if the RSE is in Amazon
• impl must set to rucio.rse.protocols.gfal.NoRename instead of the suggested rucio.rse.protocols.gfal.Default in the documentation mentioned above