update sepolia date + add TG chat

Author: isabellewei

src/content/docs/en/technology/overview/scroll-upgrades.mdx

@@ -17,6 +17,8 @@ The following contracts are used to initiate upgrades and execute upgrades after
 | L2 Scroll Multisig | Scroll| [`0xEfc9D1096fb65c832207E5e7F13C2D1102244dbe`](https://scrollscan.com/address/0xEfc9D1096fb65c832207E5e7F13C2D1102244dbe)|
 | L2 Timelock | Scroll | [`0xf6069DB81239E5194bb53f83aF564d282357bc99`](https://scrollscan.com/address/0xf6069DB81239E5194bb53f83aF564d282357bc99)|
 
+You can join our [Telegram channel for technical updates](https://t.me/scroll_tech_updates), which includes future upgrade announcements and on-chain operation events.
+
 ## Bernoulli Upgrade
 
 ### Overview
@@ -26,7 +28,7 @@ This upgrade features a significant reduction in transaction costs by introducin
 ### Timeline
 
 - **Scroll Sepolia**
-	- Network Upgrade: April 24th, 2024
+	- Network Upgrade: April 15th, 2024
 - **Scroll Mainnet**
 	- TBD