Typos (#4851)

# Fixed typos (issues #4818 & #4668 & more typos)
- At some places, it said `model = ChatOpenAI(model='gpt-3.5-turbo')`
but should be `model = ChatOpenAI(model_name='gpt-3.5-turbo')`
- Fixes some other typos

Fixes #4818, #4668

## Who can review?
Community members can review the PR once tests pass. Tag
maintainers/contributors who might be interested:
        Models
        - @hwchase17
        - @agola11
        Agents / Tools / Toolkits
        - @vowelparrot

docs/modules/agents/agents/custom_agent.ipynb

@@ -1,6 +1,7 @@
 {
  "cells": [
   {
+   "attachments": {},
    "cell_type": "markdown",
    "id": "ba5f8741",
    "metadata": {},
@@ -9,7 +10,7 @@
     "\n",
     "This notebook goes through how to create your own custom agent.\n",
     "\n",
-    "An agent consists of three parts:\n",
+    "An agent consists of two parts:\n",
     "    \n",
     "    - Tools: The tools the agent has available to use.\n",
     "    - The agent class itself: this decides which action to take.\n",

docs/modules/indexes/retrievers/examples/wikipedia.ipynb

@@ -1,6 +1,7 @@
 {
  "cells": [
   {
+   "attachments": {},
    "cell_type": "markdown",
    "id": "9fc6205b",
    "metadata": {},
@@ -13,6 +14,7 @@
    ]
   },
   {
+   "attachments": {},
    "cell_type": "markdown",
    "id": "51489529-5dcd-4b86-bda6-de0a39d8ffd1",
    "metadata": {},
@@ -21,6 +23,7 @@
    ]
   },
   {
+   "attachments": {},
    "cell_type": "markdown",
    "id": "1435c804-069d-4ade-9a7b-006b97b767c1",
    "metadata": {},
@@ -41,6 +44,7 @@
    ]
   },
   {
+   "attachments": {},
    "cell_type": "markdown",
    "id": "6c15470b-a16b-4e0d-bc6a-6998bafbb5a4",
    "metadata": {},
@@ -54,6 +58,7 @@
    ]
   },
   {
+   "attachments": {},
    "cell_type": "markdown",
    "id": "ae3c3d16",
    "metadata": {},
@@ -62,6 +67,7 @@
    ]
   },
   {
+   "attachments": {},
    "cell_type": "markdown",
    "id": "6fafb73b-d6ec-4822-b161-edf0aaf5224a",
    "metadata": {},
@@ -145,6 +151,7 @@
    ]
   },
   {
+   "attachments": {},
    "cell_type": "markdown",
    "id": "2670363b-3806-4c7e-b14d-90a4d5d2a200",
    "metadata": {},
@@ -161,7 +168,7 @@
    },
    "outputs": [
     {
-     "name": "stdin",
+     "name": "stdout",
      "output_type": "stream",
      "text": [
       " ········\n"
@@ -202,7 +209,7 @@
     "from langchain.chat_models import ChatOpenAI\n",
     "from langchain.chains import ConversationalRetrievalChain\n",
     "\n",
-    "model = ChatOpenAI(model='gpt-3.5-turbo') # switch to 'gpt-4'\n",
+    "model = ChatOpenAI(model_name='gpt-3.5-turbo') # switch to 'gpt-4'\n",
     "qa = ConversationalRetrievalChain.from_llm(model,retriever=retriever)"
    ]
   },