Fixed mypyc github link (python#7387)

tusharsadhwani · ilevkivskyi · commit eeb32dda3d28 · 2019-08-24T15:36:44.000+01:00
diff --git a/README.md b/README.md
@@ -265,7 +265,7 @@ Compiled version of mypy
 ------------------------
 
 We have built an compiled version of mypy using the [mypyc
-compiler](https://github.com/python/mypy/files/mypyc) for
+compiler](https://github.com/python/mypy/tree/master/mypyc) for
 mypy-annotated Python code. It is approximately 4 times faster than
 interpreted mypy and is available (and the default) for 64-bit
 Windows, macOS, and Linux.
