Update README.md

python/README.md

+make these executable:  
+   chmod +x pcb.py  
+   chmod +x frep.py  
+
+execute:  
+   pcb.py | frep.py  
+
+view:  
+   out.png
+
+optional arguments:  
+   pcb.py | frep.py dpi  
+   pcb.py | frep.py dpi filename  
+
+dependencies:  
+   Python  
+   NumPy  
+   Python Imaging Library  
\ No newline at end of file