Update link to rollups section.

Author: ehuss

src/libs/maintaining-std.md

@@ -248,4 +248,4 @@ Where `unsafe` and `const` is involved, e.g., for operations which are "unconst"
 [RFC 1023]: https://rust-lang.github.io/rfcs/1023-rebalancing-coherence.html
 [RFC 1105]: https://rust-lang.github.io/rfcs/1105-api-evolution.html
 [Everyone Poops]: http://cglab.ca/~abeinges/blah/everyone-poops
-[rollup guidelines]: ../compiler/reviews.md
+[rollup guidelines]: ../compiler/reviews.md#rollups