docs: Presign URLs are compatible with any storage class

[jriouovh]

Description

• Remove the note on cloud_project_region_storage_presign resource telling it's compatible only with the High Performance storage class. Pre-signed URLs are compatible with any class.
• Region name must be in uppercase

Type of change

Please delete options that are not relevant.

• Documentation update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings or issues
• I have added acceptance tests that prove my fix is effective or that my feature works
• New and existing acceptance tests pass locally with my changes
• I ran succesfully go mod vendor if I added or modify go.mod file

[dmsimard]

If the region must be in uppercase, should the terraform provider take care of putting it in uppercase if it was supplied in lower case ?

for example here:

terraform-provider-ovh/ovh/resource_cloud_project_region_storage_presign.go

Line 76 in 5bbcd92

regionName := d.Get("region_name").(string)

This would prevent confusion when some documentation state that regions must be in lower case: https://help.ovhcloud.com/csm?id=kb_article_view&sysparm_article=KB0047384

[amstuta]

This seems like a good idea: #772 :)