Update link to external document

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167781 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/CompilerWriterInfo.rst b/docs/CompilerWriterInfo.rst
index e41f5f9..7504d3c 100644
--- a/docs/CompilerWriterInfo.rst
+++ b/docs/CompilerWriterInfo.rst
@@ -87,7 +87,7 @@
 Other x86-specific information
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-* `Calling conventions for different C++ compilers and operating systems  <http://www.agner.org/assem/calling_conventions.pdf>`_
+* `Calling conventions for different C++ compilers and operating systems  <http://www.agner.org/optimize/calling_conventions.pdf>`_
 
 Other relevant lists
 --------------------