Add /mcp authentication instruction for Claude Code (#4150)

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: ethanruhe

docs/with-ai.mdx

@@ -29,7 +29,7 @@ To add it to a specific project only (stored in `.mcp.json`):
 claude mcp add --transport http temporal-docs https://temporal.mcp.kapa.ai
 ```
 
-After adding, restart Claude Code for the changes to take effect.
+After adding, restart Claude Code and run `/mcp` to authenticate with your Google account.
 
 ## Claude Desktop