[#77] readme: add aws-cli usage

Signed-off-by: Angira Kekteeva <kira@nspcc.ru>

README.md

@@ -238,6 +238,91 @@ secret stored on the NeoFS network:
 }
 ```
 
+## AWS CLI usage
+
+### Configuration
+
+#### Credentials
+
+To configure basic settings that the AWS CLI uses to interact with the Gateway, do the following steps:
+
+1. issue a secret with neofs-authmate tool (see [NeoFS Authmate] (#neofs-authmate))
+2. execute the command
+```
+$ aws configure
+```
+after you enter this command, the AWS CLI will prompt you for four pieces of information, like in this example
+(replace with your own values):
+```
+AWS Access Key ID [None]: 5g933dyLEkXbbAspouhPPTiyLZRg4axBW1axSPD87eVT_AiXsH4AjYy1iTJ4C1WExzjBrSobJsQFWEyKLREe5sQYM
+AWS Secret Access Key [None]: 438bbd8243060e1e1c9dd4821756914a6e872ce29bf203b68f81b140ac91231c
+Default region name [None]: ru 
+Default output format [none]: json 
+```
+
+### Basic usage
+
+> **_NOTE:_** To specify IP and port of the gate, append `--endpoint-url https://%IP:%PORT` to your commands.
+
+#### Bucket
+
+##### Obtainment of a list of buckets 
+
+To view the list of the buckets in the NeoFS node, to which the gateway is connected, enter the command:
+```
+$ aws s3 ls 
+```
+
+##### Creation of a bucket
+
+At this moment, the gateway supports only canned ACL and doesn't support the setting of location constraints.
+
+To create a bucket, run the command:
+```
+$ aws s3api create-bucket --bucket %BUCKET_NAME --acl %ACL
+```
+where `%ACL` can be represented by a hex encoded value or by keywords `public-read-write`, `private`, `public-read`. 
+If the parameter is not set, the default value is `private`.
+
+
+
+##### Deletion of a bucket 
+
+To delete a bucket, execute the following command:
+```
+$ aws s3api delete-bucket --bucket %BUCKET_NAME
+```
+
+#### Object
+
+##### Obtainment of a list of objects
+
+To view the list of the objects in a bucket, run:
+```
+$ aws s3api list-objects --bucket %BUCKET_NAME 
+```
+
+##### Upload of a file
+
+To upload the file into a bucket in the NeoFS network, run the following command:
+```
+$ aws s3api put-object --bucket %BUCKET_NAME --key %OBJECT_KEY --body  %FILEPATH
+```
+where %OBJECT_KEY is a filename of an object in NeoFS
+
+#### Download of a file
+
+To download the file from a bucket in the NeoFS Network, execute:
+```
+$ aws s3api get-object --bucket  %BUCKET_NAME --key %OBJECT_KEY
+```
+
+#### Deletion of a file
+To delete the file:
+```
+$ aws s3api delete-object --bucket %BUCKET_NAME --key %FILE_NAME
+```
+
 ## S3 API supported
 
 Reference: