Update readme for paddlenlp research (#2745)

PaddleNLP/Research/README.md

 ## PaddleNLP for Research
-Provide the most advanced, powerful and professional research papers.
-Fully open code and datasets to enable researchers to quickly understand the NLP frontier direction and information.
+
+- Provide the codes and the datasets of the latest research on natural language processing.
+
+- Enable the developers and researchers to easily reproduce the experiments of the published academic papers and quickly develop their new methods.