Insert additional escaping \ to windows path in docs.

PiperOrigin-RevId: 229808359

site/docs/toolchains.md

diff --git a/site/docs/toolchains.md b/site/docs/toolchains.md
index 5fe1993..510c279 100644
--- a/site/docs/toolchains.md
+++ b/site/docs/toolchains.md
@@ -263,7 +263,7 @@
         # Different flags, no debug support on windows.
     ],
     compiler_path = "C:\\path\\on\\windows\\barc.exe",
-    system_lib = "C:\\path\\on\windows\\barclib.dll",
+    system_lib = "C:\\path\\on\\windows\\barclib.dll",
 )
 ```