docs(notifying-through-ntfy): add scheduled notification support

Amolith created 

Document X-At and X-In headers for delayed notifications with examples
for both duration-based (X-In) and absolute time (X-At) scheduling.

Change summary

skills/notifying-through-ntfy/SKILL.md | 17 +++++++++++++++++
1 file changed, 17 insertions(+)

Detailed changes

skills/notifying-through-ntfy/SKILL.md 🔗 

@@ -29,6 +29,7 @@ Set headers on every notification:
   - 4 (high): long vibration burst
   - 5 (max/urgent): very long vibration burst, may bypass Do Not Disturb
 - **Click** (`-H "Click: ..."`) — optional URL opened when the notification is tapped. If your environment provides a way to generate a link back to the current conversation or session, include it. If not, only set this header when linking to something directly relevant (a PR, a deploy, a docs page, etc.). Never fabricate a conversation URL.
+- **Delay** (`-H "X-At: ..."` or `-H "X-In: ..."`) — optional delay before the notification is delivered. Accepts durations (`30m`, `2h`, `1 day`), Unix timestamps, or natural language times (`10am`, `tomorrow 3pm`, `Tuesday 7am`). Minimum 10 seconds, maximum 3 days.
 
 ## Body
 
@@ -67,6 +68,22 @@ curl -H "Authorization: Bearer $NTFY_ACCESS_TOKEN" \
   -H "Priority: 5" \
   -d "The primary Postgres instance stopped responding during a migration. Rolled back what we could, but the app is down." \
   "https://ntfy.sh/$NTFY_TOPIC_LLM"
+
+# scheduled notification (delivered in 5 minutes)
+curl -H "Authorization: Bearer $NTFY_ACCESS_TOKEN" \
+  -H "Title: CodeRabbit rate limit cleared" \
+  -H "Tags: hourglass" \
+  -H "X-In: 5m" \
+  -d "The rate limit has expired and you can retry the review now." \
+  "https://ntfy.sh/$NTFY_TOPIC_LLM"
+
+# scheduled for a specific time
+curl -H "Authorization: Bearer $NTFY_ACCESS_TOKEN" \
+  -H "Title: Standup reminder" \
+  -H "Tags: alarm_clock" \
+  -H "X-At: 9am" \
+  -d "Daily standup starts in 15 minutes." \
+  "https://ntfy.sh/$NTFY_TOPIC_LLM"
 ```
 
 ## Alternative HTTP clients