docs: add llm docs

Author: ionmincu

docs/chat_models.md

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+# UiPath chat models
+
+UiPath provides two chat models `UiPathAzureChatOpenAI` and `UiPathNormalizedChatModel`. These are compatible with langgraph as drop in replacements. You do not need to add tokens from OpenAI or Anthropic, usage of these chat models will consume `AI Units` on your account.
+
+## UiPathAzureChatOpenAI
+
+`UiPathAzureChatOpenAI` can be used as a drop in replacement for `ChatOpenAI` or `AzureChatOpenAI`. 
+
+### Example usage
+
+Here is a code that is using `ChatOpenAI`
+```python
+from langchain_openai import ChatOpenAI
+
+llm = ChatOpenAI(
+    model="gpt-4o",
+    temperature=0,
+    max_tokens=None,
+    timeout=None,
+    max_retries=2,
+    # api_key="...",  # if you prefer to pass api key in directly instaed of using env vars
+    # base_url="...",
+    # organization="...",
+    # other params...
+)
+```
+
+You can simply change `ChatOpenAi` with `UiPathAzureChatOpenAI`, you don't have to provide an `OPEN_AI_TOKEN`
+
+
+```python
+from uipath_langchain.chat.models import UiPathAzureChatOpenAI
+
+llm = UiPathAzureChatOpenAI(
+    model="gpt-4o",
+    temperature=0,
+    max_tokens=None,
+    timeout=None,
+    max_retries=2,
+    # other params...
+)
+```
+
+Currently the following models can be used with `UiPathAzureChatOpenAI` (this list can be updated in the future): 
+- `gpt-4`, `gpt-4-1106-Preview`, `gpt-4-32k`, `gpt-4-turbo-2024-04-09`, `gpt-4-vision-preview`, `gpt-4o-2024-05-13`, `gpt-4o-2024-08-06`, `gpt-4o-mini-2024-07-18`, `o3-mini-2025-01-31`
+
+
+## UiPathNormalizedChatModel
+
+`UiPathNormalizedChatModel` is a more versatile clas that can suport models from diferent vendors including OpenAI.
+
+### Example usage
+
+Given the following code:
+
+```python
+from langchain_anthropic import ChatAnthropic
+
+llm = ChatAnthropic(
+    model="claude-3-5-sonnet-20240620",
+    temperature=0,
+    max_tokens=1024,
+    timeout=None,
+    max_retries=2,
+    # other params...
+)
+```
+
+You can replace it with `UiPathNormalizedChatModel` like so:
+
+```python
+from uipath_langchain.chat.models import UiPathNormalizedChatModel
+
+llm = UiPathNormalizedChatModel(
+    model="anthropic.claude-3-opus-20240229-v1:0",
+    temperature=0,
+    max_tokens=1024,
+    timeout=None,
+    max_retries=2,
+    # other params...
+)
+```
+
+Currently the following models can be used with `UiPathAzureChatOpenAI` (this list can be updated in the future): 
+- `anthropic.claude-3-5-sonnet-20240620-v1:0`, `anthropic.claude-3-5-sonnet-20241022-v2:0`, `anthropic.claude-3-7-sonnet-20250219-v1:0`, `anthropic.claude-3-haiku-20240307-v1:0`, `gemini-1.5-pro-001`, `gemini-2.0-flash-001`, `gpt-4o-2024-05-13`, `gpt-4o-2024-08-06`, `gpt-4o-2024-11-20`, `gpt-4o-mini-2024-07-18`, `o3-mini-2025-01-31`
+
+### Note 
+
+Please note that that you may get errors related to data residency, as some models are not available on all regions.
+
+Example: `[Enforced Region] No model configuration found for product uipath-python-sdk in EU using model anthropic.claude-3-opus-20240229-v1:0`.