fix(examples): correct formatting, grammar, and MMLU acronym in llama_chroma_qa example

[Rahul-Lashkari]

Description of the change

Corrects minor formatting, grammar, and a factual error within the examples/gemini/python/llamaindex/Gemini_LlamaIndex_QA_Chroma_WebPageReader.ipynb example notebook.

Specifically:

• Added space before parenthesis in Model (LLM).
• Fixed grammar with a variety of.
• Corrected the expansion of the MMLU acronym in a code comment.

Motivation

To improve the readability, grammatical correctness, and factual accuracy of the example notebook.

Type of change

Documentation

Checklist

• [x] I have performed a self-review of my code.
• [x] I have added detailed comments to my code where applicable.
• [x] I have verified that my change does not break existing code.
• [x] My PR is based on the latest changes of the main branch (if unsure, please run git pull --rebase upstream main).
• [x] I am familiar with the Google Style Guide for the language I have coded in.
• [x] I have read through the Contributing Guide and signed the Contributor License Agreement.