Apply suggestions from code review

Author: m-mohr

platforms/aws-s3.md

@@ -7,5 +7,5 @@ This defines the Amazon Web Services (AWS) S3 interface.
 - `bucket`: The bucket name.
 - `region`: One of the S3 regions (lowercase).
 
-**Note:** If `s3` exists in `auth:refs`, you should use sign requests,
+**Note:** If the `s3` authentication scheme (i.e. "Simple S3 authentication") is referred to through `auth:refs`, you should disable signing requests,
 e.g. using the AWS CLI parameter `--no-sign-request`.

platforms/custom-s3.md

@@ -14,11 +14,12 @@ GDAL documentation: <https://gdal.org/en/latest/user/virtual_file_systems.html#v
 
 - `platform`: Some options for S3 can be inferred from the given URL (template):
   - `AWS_HTTPS` can be retrieved by parsing the scheme part of the URL. `https` = `ON`, `http` = `OFF`.
-  - `AWS_S3_ENDPOINT` is the authority part of the URL after replacing all variables in the URL.
+  - `AWS_S3_ENDPOINT` is the authority part of the URL after replacing all variables in the URL, e.g. `us-west.mycloud.com` without `https://` or `s3://` as prefix.
   - `AWS_VIRTUAL_HOSTING` must be set to `FALSE` if there's no `{bucket}` placeholder in the URL template, otherwise `TRUE` (default value).
 - The `region` property corresponds to the `AWS_REGION` option.
 - The `requester_pays` property corresponds to the `AWS_REQUEST_PAYER` option. If `requester_pays` is `true`, set `AWS_REQUEST_PAYER` to `requester`.
-- If `s3` exists in `auth:refs`, you should set `AWS_NO_SIGN_REQUEST` to `YES`. Otherwise it should be `NO`.
+- If the `s3` authentication scheme (i.e. "Simple S3 authentication") is referred to through `auth:refs`,
+   you should set `AWS_NO_SIGN_REQUEST` to `NO`. Otherwise it should be `YES`.
 
 ### AWS CLI
 
@@ -35,4 +36,5 @@ s3cmd documentation: <https://s3tools.org/usage>
 - `platform` corresponds to `--host` / `--host-bucket` after replacing all variables in the URL (?).
 - `region` corresponds to `--region`.
 - `requester_pays` corresponds to `--requester-pays`.
-- If `s3` exists in `auth:refs`, you should use the `s3cmd sign` command.
+- If the `s3` authentication scheme (i.e. "Simple S3 authentication") is referred to through `auth:refs`,
+   you should provide an secret access key and an access key id through environment variables, a profile or the `s3cmd sign` command.