Averages in Embedding_long_inputs.ipynb are weighted by vector length

[JMVaughan]

The notebook Embedding_long_inputs.ipynb performs a weighted average of the embeddings by length of vector, however I believe the average should be weighted by length of chunk.

[ted-at-openai]

Great catch. @filipeabperes, do you want to fix this?

[filipeabperes]

❗ on it