docs: improve content based on Ask Fern feedback

Author: dannysheridan

fern/products/ask-fern/pages/features/slack-app.mdx

@@ -47,6 +47,14 @@ Once you've installed it in your workspace, add the bot to customer Slack channe
 </Step>
 </Steps>
 
+## Using Ask Fern
+
+Once Ask Fern is installed in your workspace and added to channels, users can interact with it in several ways:
+
+- **Use the `/fern` command** in any channel to ask a question directly
+- **Mention the bot** with `@Ask Fern` followed by your question
+- **Ask questions naturally** in channels where the bot is configured to respond to all messages (see Configuration below)
+
 ## Configuration
 
 Customize the bot's behavior to match your workflow needs.
@@ -163,5 +171,4 @@ sequenceDiagram
     A->>U: Return answer in Slack thread
     F->>F: Store question and answer for analytics
 ```
-</Accordion>
-
+</Accordion>