Use unique label

Author: markshannon

peps/pep-0805.rst

@@ -255,7 +255,7 @@ To synchronize a Python module, add this code::
     __module__.synchronize()
 
 Extension modules can declare themselves *immutable* or *synchronized*
-using the `C-API`_\.
+using the `pep805_capi`_\.
 
 Where possible, modules should be frozen.
 
@@ -715,7 +715,7 @@ Primitive types have the following properties:
 * A context switch will not occur during operations on them
 * Their reclamation may be deferred once they are no longer referenced
 
-.. _C-API:
+.. _pep805_capi:
 
 C Extensions and the C API
 --------------------------