Update README.rst
Update README.rst

Added a link to the DG_Boundary.rst under "DataGenerator specific tags"
jeanmusinski/DataGenerator,mauriciosilva1990/DataGenerator,Brijeshrpatel9/DataGenerator,santiagos11/DataGenerator,leeny324/DataGenerator,mibrahim/DataGenerator,SamerAdra/DataGenerator,FINRAOS/DataGenerator,Brijeshrpatel9/DataGeneratorFinal,yukaReal/DataGenerator