Link issue on 10kb GM12878 model

In the file models/Readme.md the 10kb GM12878 combined model has same url as the primary one:

```
* 10 kb resolution
  * [GM12878_primary](http://datashare.molbiol.ox.ac.uk/public/rschwess/deepC/models/model_deepCregr_10kb_GM12878_primary.tar.gz)
  * [GM12878_combined](http:/datashare.molbiol.ox.ac.uk/public/rschwess/deepC/models/model_deepCregr_10kb_GM12878_primary.tar.gz)
``` 