Add example demonstrating using openai & cohere embeddings

[fr0th]

Description of changes

Summarize the changes made by this PR. Add an example notebook to demonstrate using both openai & cohere embeddings with the 'getting started' example from docs

Test plan

n/a

Documentation Changes

Are all docstrings for user-facing APIs updated if required? Do we need to make documentation changes in the docs repository?

n/a

[HammadB]

Thank @fr0th - can we add examples for the other embedding functions here? InstructorEmbeddingFunction, HuggingFaceEmbeddingFunction

[fr0th]

Thank @fr0th - can we add examples for the other embedding functions here? InstructorEmbeddingFunction, HuggingFaceEmbeddingFunction

Have added both examples now.

Note: Have only included results output for huggingface. If someone here has InstructorEmbedding setup and can add output that would be awesome.

[jeffchuber]

Note to self: pull down and check out notebook locally