[DOCS] Describe differences between connector types

docs/management/connectors/action-types/slack.asciidoc

@@ -4,31 +4,29 @@
 <titleabbrev>Slack</titleabbrev>
 ++++
 
-The Slack connector uses https://api.slack.com/incoming-webhooks[Slack Incoming Webhooks].
+The Slack connector uses incoming webhooks or an API method to send Slack messages.
 
 [float]
 [[define-slack-ui]]
 === Create connectors in {kib}
 
-You can create connectors in *{stack-manage-app} > {connectors-ui}*
-or as needed when you're creating a rule. For example:
+You can create connectors in *{stack-manage-app} > {connectors-ui}* or as needed when you're creating a rule.
+You can choose to use a webhook URL that's specific to a single user or channel. For example:
 
 [role="screenshot"]
 image::management/connectors/images/slack-webhook-connector.png[Slack connector]
 // NOTE: This is an autogenerated screenshot. Do not edit it directly.
 
-//TBD Describe reason for choosing one or other type of Slack connector
+Alternatively, you can create a connector that supports multiple channels. For example:
 
 [role="screenshot"]
 image::management/connectors/images/slack-api-connector.png[Slack API connector]
 // NOTE: This is an autogenerated screenshot. Do not edit it directly.
 
-[float]
-[[slack-connector-configuration]]
-==== Connector configuration
+If you use the latter method, you choose your channels when you create rule actions.
+Thus a connector can be used in multiple rules to communicate with different channels.
 
-Slack connectors have a name and either a webhook URL or an API token.
-To set up your Slack account and obtain these values, go to <<configuring-slack>>.
+For Slack setup details, go to <<configuring-slack>>.
 
 [float]
 [[preconfigured-slack-configuration]]
@@ -75,16 +73,18 @@ image::management/connectors/images/slack-api-params.png[Slack API connector tes
 Slack actions have the following properties:
 
 Channels::
-//TBD
-// Note that it's only applicable to the web API type of Slack connector
+One or more channels that your Slack app has access to.
+This option is available only in the web API type of connector.
 
-Message:: The message	text, converted to the `text` field in the Webhook JSON payload. Currently only the text field is supported. Markdown, images, and other advanced formatting are not yet supported.
+Message:: The message	text, converted to the `text` field in the Webhook JSON payload.
+Currently only the text field is supported. Markdown, images, and other advanced formatting are not yet supported.
 
 [float]
 [[slack-connector-networking-configuration]]
 === Connector networking configuration
 
-Use the <<action-settings,Action configuration settings>> to customize connector networking configurations, such as proxies, certificates, or TLS settings. You can set configurations that apply to all your connectors or use `xpack.actions.customHostSettings` to set per-host configurations.
+Use the <<action-settings,Action configuration settings>> to customize connector networking configurations, such as proxies, certificates, or TLS settings.
+You can set configurations that apply to all your connectors or use `xpack.actions.customHostSettings` to set per-host configurations.
 
 [float]
 [[configuring-slack]]
@@ -94,7 +94,7 @@ Before you can create a Slack connector, you must configure your account and obt
 
 [float]
 [[configuring-slack-webhook]]
-==== Configure a Slack account with Webhook
+==== Configure a Slack account for incoming webhooks
 
 . Log in to http://slack.com[slack.com] as a team administrator.
 . Create a Slack app, enable incoming webhooks, then create an incoming webhook. Refer to https://api.slack.com/messaging/webhooks.
@@ -103,7 +103,7 @@ Before you can create a Slack connector, you must configure your account and obt
 
 [float]
 [[configuring-slack-web-api]]
-==== Configure a Slack account with Web API
+==== Configure a Slack account for Web API
 
 . Create a Slack app. Refer to https://api.slack.com/authentication/basics#creating.
 . Add scope: `channels:read`, `groups:read`, `chat:write` and `chat:write.public`. Refer to https://api.slack.com/authentication/basics#scopes.