fix a link issue in getting_started.md

docs/cn/getting_started.md

@@ -46,7 +46,7 @@ The over-aligned issues in GCC7 is suppressed temporarily now.
 
 Using other versions of gcc may generate warnings, contact us to fix.
 
-Adding `-D__const__=` to cxxflags in your makefiles is a must avoid [errno issue in gcc4+](docs/thread_local.md)。
+Adding `-D__const__=` to cxxflags in your makefiles is a must avoid [errno issue in gcc4+](thread_local.md)。
 
 ## Clang: 3.5-4.0