readme: Label mappings
  {'LABEL_0':'Biology','LABEL_1':'Physics','LABEL_2':'Chemistry','LABEL_3':'Maths','LABEL_4':'Social Science','LABEL_5':'English'}
  
  Training data distribution
  Physics - 7000
  Maths   - 7000
  Biology - 7000
  Chemistry - 7000
  English - 5254
  Social Science - 7000