Update en page components

- Index page event group link
- Guide page event group section and buttons
- Guide page souvenir customization button

Signed-off-by: Asai Neko <sugar@sne.moe>

src/content/docs/en/index.mdx

@@ -10,12 +10,7 @@ hero:
         - text: 'Meetup #2 Attendee Guide'
           link: /en/meetup-2-guide
           icon: right-arrow
-        - text: Join the Telegram event group
+        - text: Join event group
-          link: https://t.me/nixcnmeetup
+          link: /en/meetup-2-guide#event-groups
-          icon: external
-          variant: minimal
-        - text: Join the Matrix event group
-          link: https://matrix.to/#/#nix-cn-meetup:rebmit.moe
-          icon: external
           variant: minimal
 ---

src/content/docs/en/meetup-2-guide.mdx

@@ -21,8 +21,17 @@ Nix CN Meetup #2 is the second Nix-themed gathering in China. We aim to bring to
 <LinkButton href='https://www.wjx.top/vm/Qi3eqxV.aspx' icon='external' variant='secondary' iconPlacement='end'>
     Propose a talk (Chinese)
 </LinkButton>
-<LinkButton href='#' icon='external' variant='secondary' iconPlacement='end'>
+<LinkButton href='/en/souvenir-customization/' icon='external' variant='secondary' iconPlacement='end'>
-    Name Badge Customization Request (Coming Soon)
+    Souvenir Customization
+</LinkButton>
+
+## Event Groups
+
+<LinkButton href='https://t.me/nixcnmeetup' icon='telegram' variant='secondary' iconPlacement='start'>
+    Telegram event group
+</LinkButton>
+<LinkButton href='https://matrix.to/#/#nix-cn-meetup:rebmit.moe' icon='matrix' variant='secondary' iconPlacement='start'>
+    Matrix event group
 </LinkButton>
 
 ## Transportation