Add funder info about trainset

[daterdots]

@ajaypillarisetti can you give us the correct organization + grant# to acknowledge?

[ajaypillarisetti]

No grant number -- asked for the agreement number. In the interim, let's use this language: This work was supported by the Implementation Science Network of the US National Institutes of Health.

[daterdots]

TRAINSET was supported by the Implementation Science Network of the US National Institutes of Health. The development of SUMSarizer, which TRAINSET is based on, was supported by the Center for Effective Global Action (CEGA) and Innovations for Poverty Action (IPA).