add doc for compute_norms
add doc for compute_norms

Richi91/nntools,mheilman/Lasagne,cancan101/Lasagne,rlkelly/Lasagne,gabortakacs/Lasagne,takacsg84/Lasagne,ebattenberg/Lasagne,diogo149/Lasagne,kracwarlock/Lasagne,ErnstHowie/Lasagne,DeanChan/Lasagne,dnuffer/Lasagne,DataFighter/Lasagne-tutorial,MihailoIsakov/fishfish