fix wrong link

Author: bombless

src/doc/trpl/macros.md

@@ -571,7 +571,7 @@ intermediate states out, and passing the flag `--pretty expanded` as a
 command-line argument to the compiler will show the result of expansion.
 
 If Rust's macro system can't do what you need, you may want to write a
-[compiler plugin](plugin.html) instead. Compared to `macro_rules!`
+[compiler plugin](plugins.html) instead. Compared to `macro_rules!`
 macros, this is significantly more work, the interfaces are much less stable,
 and the warnings about debugging apply ten-fold. In exchange you get the
 flexibility of running arbitrary Rust code within the compiler. Syntax