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README.md

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 ## Introduction
 This is an NWB extension for storing photometry recordings and associated metadata. This extension stores photometry information across three folders in the NWB file: acquisition, processing, and general. The acquisiton folder contains an ROIResponseSeries (inherited from `pynwb.ophys`), which references rows of a FibersTable rather than 2 Photon ROIs. The new types for this extension are in metadata and processing