Update intro to same thread example, update conceptual docs to include checkpoint (#827)

examples/cloud_examples/same-thread.ipynb

@@ -7,9 +7,13 @@
    "source": [
     "# How to run multiple agents on the same thread\n",
     "\n",
-    "In LangGraph API, a thread is not explicitly associated with a particular agent.\n",
-    "This means that you can run multiple agents on the same thread.\n",
-    "In this example, we will create two agents and then call them both on the same thread."
+    "In LangGraph Cloud, a thread is not explicitly associated with a particular agent.\n",
+    "This means that you can run multiple agents on the same thread, which allows a different\n",
+    "agent to continue from an initial agent's progress.\n",
+    "\n",
+    "In this example, we will create two agents and then call them both on the same thread.\n",
+    "You'll see that the second agent will respond using information from the [checkpoint](https://langchain-ai.github.io/langgraph/concepts/low_level/#checkpointer-state) generated in the thread\n",
+    "by the first agent as context."
    ]
   },
   {
@@ -37,7 +41,7 @@
    "id": "4f10d346-69e6-44f4-8ff0-ef539ba938df",
    "metadata": {},
    "source": [
-    "We can see that these agents are different"
+    "We can see that these agents are different:"
    ]
   },
   {
@@ -97,7 +101,7 @@
    "id": "5e655e61-c2ee-488a-90f6-6189c84841da",
    "metadata": {},
    "source": [
-    "We can now run it on the OpenAI assistant first."
+    "We can now run the OpenAI assistant on the thread first."
    ]
   },
   {
@@ -133,7 +137,7 @@
    "id": "c53709e9-ddb2-4429-9042-456eb6c91244",
    "metadata": {},
    "source": [
-    "Now, we can run it on a different Anthropic-based assistant."
+    "Now, we can run it on a second Anthropic-based assistant and see that this second assistant is aware of the initial question, and can answer the question, `and you?`:"
    ]
   },
   {