docs: Advertise Slack-compatible webhook a bit.

This should make it discoverable enough that users will try it out and
send us feedback.

templates/zerver/api/incoming-webhooks-overview.md

@@ -1,13 +1,18 @@
 # Incoming webhook integrations
 
 An incoming webhook allows a third-party service to push data to Zulip when
-something happens.  There's two ways to do an incoming webhook in
+something happens.  There's several ways to do an incoming webhook in
 Zulip:
 
 * Use our [REST API](/api/rest) endpoint for [sending
   messages](/api/send-message).  This works great for internal tools
   or cases where the third-party tool wants to control the formatting
   of the messages in Zulip.
+* Use one of our supported [integration
+  frameworks](/integrations/doc/meta-integration), such as the
+  [Slack-compatible incoming webhook](/integrations/doc/slack_incoming),
+  [Zapier integration](/integrations/docs/zapier), or
+  [IFTTT integration](/integrations/doc/ifttt).
 * Adding an incoming webhook integration (detailed on this page),
   where all the logic for formatting the Zulip messages lives in the
   Zulip server.  This is how most of [Zulip's official

templates/zerver/api/integrations-overview.md

@@ -28,6 +28,11 @@ Zulip.
   product. If it does, follow [these instructions](/integrations/doc/ifttt)
   to set it up.
 
+* Use a third-party webhook integration designed to work with
+  [Slack's webhook API](https://api.slack.com/messaging/webhooks)
+  pointed at Zulip's
+  [Slack-compatible webhook API](/integrations/slack/slack_incoming).
+
 * Check if [Hubot](https://github.com/hubot-scripts) has an integration with
   the product. If it does, follow
   [these instructions](/integrations/doc/hubot) to set it up.

templates/zerver/help/import-from-slack.md

@@ -109,3 +109,7 @@ root domain. Replace the last line above with the following, after replacing
 - The "joined #channel_name" messages are not imported.
 
 [upgrade-zulip-from-git]: https://zulip.readthedocs.io/en/latest/production/upgrade-or-modify.html#upgrading-from-a-git-repository
+
+## Related articles
+
+- [Slack-compatible incoming webhook](/integrations/doc/slack_incoming)

zerver/lib/integrations.py

@@ -363,7 +363,7 @@ WEBHOOK_INTEGRATIONS: List[WebhookIntegration] = [
     WebhookIntegration('sentry', ['monitoring']),
     WebhookIntegration(
         'slack_incoming',
-        ['communication'],
+        ['communication', 'meta-integration'],
         display_name="Slack-compatible webhook",
         logo='images/integrations/logos/slack.svg',
     ),

zerver/webhooks/slack/doc.md

@@ -1,6 +1,8 @@
 Get Zulip notifications from Slack for messages on your team's
 public channels!
 
+See also the [Slack-compatible webhook](/integrations/doc/slack_incoming).
+
 1. {!create-stream.md!}
 
 1. {!create-bot-construct-url-indented.md!}

zerver/webhooks/slack_incoming/doc.md

@@ -1,4 +1,6 @@
-Basic support for Slack-compatible webhooks.
+This beta Zulip integration supports for processing incoming webhook
+messages written to work with Slack's [incoming webhook
+API](https://api.slack.com/messaging/webhooks).
 
 1. {!create-stream.md!}
 
@@ -7,3 +9,18 @@ Basic support for Slack-compatible webhooks.
 1. Use your new webhook URL any place that you would use a Slack webhook.
 
 {!congrats.md!}
+
+Where possible, we prefer to create native Zulip integrations that
+make optimal use of Zulip's topics and don't require translating
+formatting, but this is a useful stopgap, especially for getting
+messages from third-party vendors that only offer a Slack integration
+(with no generic outgoing webhook API).
+
+This integration, by its nature, involves a somewhat complex
+translation between Slack's formatting system and Zulip's.  We
+appreciate [feedback and bug reports](/help/contact-support) on any
+cases where the resulting Zulip formatting is poor, so that we can
+either improve the formatting or add an appropriate native integration.
+
+See also the [Slack notifications](/integrations/doc/slack)
+integration for mirroring content from a Slack instance into Zulip.