docs: Add Slack icon and link (#7091)

Author: igorlukanin

docs/docs-new/theme.config.tsx

@@ -17,6 +17,10 @@ const config: DocsThemeConfig = {
   project: {
     link: repo,
   },
+  chat: {
+    link: 'https://slack.cube.dev',
+    icon: <svg fill="#000000" width="24" height="24" viewBox="0 0 512 512" xmlns="http://www.w3.org/2000/svg"><title>ionicons-v5_logos</title><path d="M126.12,315.1A47.06,47.06,0,1,1,79.06,268h47.06Z"/><path d="M149.84,315.1a47.06,47.06,0,0,1,94.12,0V432.94a47.06,47.06,0,1,1-94.12,0Z"/><path d="M196.9,126.12A47.06,47.06,0,1,1,244,79.06v47.06Z"/><path d="M196.9,149.84a47.06,47.06,0,0,1,0,94.12H79.06a47.06,47.06,0,0,1,0-94.12Z"/><path d="M385.88,196.9A47.06,47.06,0,1,1,432.94,244H385.88Z"/><path d="M362.16,196.9a47.06,47.06,0,0,1-94.12,0V79.06a47.06,47.06,0,1,1,94.12,0Z"/><path d="M315.1,385.88A47.06,47.06,0,1,1,268,432.94V385.88Z"/><path d="M315.1,362.16a47.06,47.06,0,0,1,0-94.12H432.94a47.06,47.06,0,1,1,0,94.12Z"/></svg>
+  },
   head: (
     <>
       <meta name="viewport" content="width=device-width, initial-scale=1.0" />