Rodney Kinney

RedPajama includes [data sourced from ArXiv](https://github.com/togethercomputer/RedPajama-Data/tree/main/data_prep/arxiv) An alternative is [unArXive](https://github.com/IllDepence/unarXive) S2's LaTex dumps from ArXiv are in `s3://ai2-s2-scholarphi-pipeline-prod/daq/arxiv-source-data/bymonth/` @kyleclo @soldni

Add mixer configuration to trim trailing/leading whitespace from document text, and enforce a minimum document text length. Place these into a new `text_modification` config object, and move the `span_replacements` config...