add docs

docs/community/app_showcase.md

docs/community/integrations.md

docs/community/integrations/chatgpt_plugins.md

docs/community/integrations/graph_stores.md

docs/community/integrations/graphsignal.md

docs/community/integrations/guidance.md

docs/community/integrations/trulens.md

docs/community/integrations/using_with_langchain.md

docs/community/integrations/vector_stores.md

docs/core_modules/agent_modules/agents/modules.md

docs/core_modules/agent_modules/agents/root.md

docs/core_modules/agent_modules/agents/usage_pattern.md

.../core_modules/agent_modules/tools/llamahub_tools_guide.md

docs/core_modules/agent_modules/tools/root.md

docs/core_modules/agent_modules/tools/usage_pattern.md

docs/core_modules/data_modules/connector/modules.md

docs/core_modules/data_modules/connector/root.md

docs/core_modules/data_modules/connector/usage_pattern.md

docs/core_modules/data_modules/documents_and_nodes/root.md

...dules/data_modules/documents_and_nodes/usage_documents.md