fix notebook path summarization and qa, add grocerybot

[eliasecchig]

PR that fixes the path to run the notebook in Colab / Workbench for:

• language/examples/document-qa/question_answering_large_documents.ipynb
• language/examples/document-qa/question_answering_large_documents_langchain.ipynb
• language/examples/document-summarization/summarization_large_documents.ipynb
• language/examples/document-summarization/summarization_large_documents_langchain.ipynb

This PR also adds GroceryBot, a sample assistant to the reference architectures folder.

[review-notebook-app[bot]]

Check out this pull request on 

See visual diffs & provide feedback on Jupyter Notebooks.

---

Powered by ReviewNB

[polong-lin]

After testing the notebook in Vertex AI Workbench, I've made some minor changes to the notebook and renamed the file to be simpler. Could you PTAL at the changes and let me know if it LGTU? Then I'll merge

[polong-lin]

Oh in the grocerybot notebook -- please run a code linter. I noticed some inconsistencies in tabbing, for example

[polong-lin]

Merging, and I will do linting in the dev branch directly