README.md: add notes to How to compile on Windows

Jud White

2018-03-25 c6ecf1e0420737eafeb99b27b1d716b46a6cbb7a

 src/cost_layer.c

@@ -31,7 +31,7 @@

cost_layer make_cost_layer(int batch, int inputs, COST_TYPE cost_type, float scale)
{
    fprintf(stderr, "Cost Layer: %d inputs\n", inputs);
    fprintf(stderr, "cost                                           %4d\n",  inputs);
    cost_layer l = {0};
    l.type = COST;