PBM-1214 Fixed Docker instructions

docs/install/docker.md

@@ -10,6 +10,11 @@
 
     By default, Docker will pull the image from Docker Hub if it is not available locally.
 
+## Prerequisites
+
+* You need to deploy MongoDB or Percona Server for MongoDB. See [what MongoDB deployments are supported](../details/deployments.md).
+* [Create the pbm user](initial-setup.md#create-the-pbm-user) in your deployment. You will need this user credentials to start Percona Backup for MongoDB container. 
+
 ## Start Percona Backup for MongoDB 
 
 Start Percona Backup for MongoDB container with the following command:
@@ -23,7 +28,7 @@
 
 * `container-name` is the name you want to assign to your container.
 * `PBM_MONGODB-URI` is a [MongoDB Connection URI](https://docs.mongodb.com/manual/reference/connection-string/) string used to connect to MongoDB nodes. See the [Initial setup](initial-setup.md) how to create the PBM user. 
-* `tag-multi` is the tag specifying the version you need. For example, `2.3.0-multi`. The `multi` part of the tag serves to identify the architecture (x86_64 or ARM64) and pull the respective image. See the [full list of tags](https://hub.docker.com/r/perconalab/percona-backup-mongodb/tags).
+* `tag-multi` is the tag specifying the version you need. For example, `{{release}}-multi`. The `multi` part of the tag serves to identify the architecture (x86_64 or ARM64) and pull the respective image. See the [full list of tags](https://hub.docker.com/r/perconalab/percona-backup-mongodb/tags).
 
 Note that every MongoDB node (including replica set secondary members and config server replica set nodes) requires a separate instance of Percona Backup for MongoDB. Thus, a typical, 3-node MongoDB replica set requires three instances of Percona Backup for MongoDB.
 
@@ -34,16 +39,22 @@
 1. Start a Bash session:
 
     ```{.bash data-prompt="$"}
-    $ docker run --name <container-name> bash
+    $ docker exec -it -u root --name <container-name> bash
     ```
 
-2. Create a YAML configuration file:
+2. Download the editor of your choice. In this example, let's use Vim 
+
+    ```{.bash data-prompt="$"}
+	$ microdnf install vim
+	```
+
+3. Create a YAML configuration file:
 
 	```{.bash data-prompt="$"}
-	$ touch /tmp/pbm_config.yaml
+	$ vim /tmp/pbm_config.yaml
 	```
 
-3. Specify remote storage parameters in the config file. The following example is for S3-compatible backup storage. Check what [other storages are supported](../details/storage-configuration.md):
+4. Specify remote storage parameters in the config file. The following example is for S3-compatible backup storage. Check what [other storages are supported](../details/storage-configuration.md) and [examples of storage configurations](../details/storage-config-example.md):
 
 	```yaml
 	storage:
@@ -56,20 +67,22 @@
 		secret-access-key: <your-secret-key-here>
 	```
 
-4. Upload the config file: 
+5. Upload the config file: 
 
 	```{.bash data-prompt="$"}
 	$ pbm config --file /tmp/pbm_config.yaml
 	```
 
+	The command output displays your uploaded configuration.
+
 ## Run Percona Backup for MongoDB
 
 Percona Backup for MongoDB command line utility (`pbm`) provides the set of commands to control backups: create, restore, cancel backups, etc. 
 
 For example, to start a backup, use the following command:
 
 ```{.bash data-prompt="$"}
-$ docker run --name <container-name> pbm backup
+$ docker exec -it --name <container-name> pbm backup
 ```
 
 where `<container-name>` is the name you assigned to the container and `pbm backup` is the command to start a backup.