docs: Update with LCEL examples to Ollama & ChatOllama Integration notebook (langchain-ai#16194)

- **Description:** Updated the Chat/Ollama docs notebook with LCEL chain
examples

- **Issue:**  langchain-ai#15664 I'm a new contributor 😊

- **Dependencies:** No dependencies

- **Twitter handle:** 

Comments:

- How do I truncate the output of the stream in the notebook if and or
when it goes on and on and on for even the basic of prompts?

Edit:

Looking forward to feedback @baskaryan

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Co-authored-by: Bagatur <[email protected]>

Author: seanmavley