Fix Signal documentation link in integrations page

Updated the documentation link for Signal integration.

Author: deftdawg

src/pages/integrations.astro

@@ -55,7 +55,7 @@ const chatProviders = [
   { name: 'Telegram', icon: siIcon(siTelegram), color: '#26A5E4', desc: 'Bot API via grammY', docs: 'https://docs.openclaw.ai/telegram' },
   { name: 'Discord', icon: siIcon(siDiscord), color: '#5865F2', desc: 'Servers, channels & DMs', docs: 'https://clawhub.com/skills/discord' },
   { name: 'Slack', icon: 'lucide:hash', color: '#E01E5A', desc: 'Workspace apps via Bolt', docs: 'https://clawhub.com/skills/slack' },
-  { name: 'Signal', icon: siIcon(siSignal), color: '#3A76F0', desc: 'Privacy-focused via signal-cli', docs: 'https://clawhub.com/skills/sag' },
+  { name: 'Signal', icon: siIcon(siSignal), color: '#3A76F0', desc: 'Privacy-focused via signal-cli', docs: 'https://docs.openclaw.ai/channels/signal' },
   { name: 'iMessage', icon: siIcon(siApple), color: '#007AFF', desc: 'iMessage via imsg (AppleScript bridge)', docs: 'https://github.com/steipete/imsg' },
   { name: 'iMessage', icon: bluebubblesIcon, color: '#3B82F6', desc: 'iMessage via BlueBubbles server', docs: 'https://docs.openclaw.ai/channels/bluebubbles' },
   { name: 'Microsoft Teams', icon: 'lucide:users', color: '#6264A7', desc: 'Enterprise support', docs: 'https://docs.openclaw.ai/msteams' },