docs: document_loaders improvements (#4200)

- made notebooks consistent: titles, service/format descriptions.
- corrected short names to full names, for example, `Word` -> `Microsoft
Word`
- added missed descriptions
- renamed notebook files to make ToC correctly sorted

docs/modules/indexes/document_loaders/examples/chatgpt_loader.ipynb

@@ -4,7 +4,10 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "### ChatGPT Data Loader\n",
+    "### ChatGPT Data\n",
+    "\n",
+    ">[ChatGPT](https://chat.openai.com) is an artificial intelligence (AI) chatbot developed by OpenAI.\n",
+    "\n",
     "\n",
     "This notebook covers how to load `conversations.json` from your `ChatGPT` data export folder.\n",
     "\n",