update protocols to include mcp and a2a#3678

Naomi Pentrel (npentrel) merged 4 commits intomainlangchain-ai/docs:mainfrom

naomi/doc-923-add-mcp-and-a2a-to-deep-agents-protocols-sectionlangchain-ai/docs:naomi/doc-923-add-mcp-and-a2a-to-deep-agents-protocols-sectionCopy head branch name to clipboard