(wip) docs: revamp conceptual docs (#1663)

* docs: revamp conceptual docs

* multi-agent draft

* typo

* Update Why LangGraph page

* update multi-agent

* Update persistence page

* update

* Clarification of graph re-playing

* update persistence

* more updates

* more updates

* Add multiple schemas section to glossary

* more updates

* Clarify I/O schema

* dynamic breakpoints

* Update agentic concepts

* Fix comments

* Update figureds

* cr

* cr

* cr

---------

Co-authored-by: Lance Martin <lance@langchain.dev>
Co-authored-by: Harrison Chase <hw.chase.17@gmail.com>

docs/mkdocs.yml

@@ -189,10 +189,13 @@ nav:
           - Add Human-in-the-loop to a ReAct agent: how-tos/create-react-agent-hitl.ipynb
           - Create prebuilt ReAct agent from scratch: how-tos/react-agent-from-scratch.ipynb
   - "Conceptual Guides":
-      - "concepts/index.md"
-      - LangGraph for Agentic Applications: concepts/high_level.md
-      - Low Level LangGraph Concepts: concepts/low_level.md
+      - Why LangGraph?: concepts/high_level.md
+      - LangGraph Glossary: concepts/low_level.md
       - Common Agentic Patterns: concepts/agentic_concepts.md
+      - Human-in-the-Loop: concepts/human_in_the_loop.md
+      - Multi-Agent Systems: concepts/multi_agent.md
+      - Persistence: concepts/persistence.md
+      - Streaming: concepts/streaming.md
       - FAQ: concepts/faq.md
   - Reference:
       - Graphs: reference/graphs.md