fix links

Author: jdonszelmann

src/solve/invariants.md

@@ -113,7 +113,7 @@ in the trait solver
 
 #### The type system is complete during the implicit negative overlap check in coherence ✅
 
-For more on overlap checking: [./overlap.md]
+For more on overlap checking: [../coherence.md]
 
 During the implicit negative overlap check in coherence we must never return *error* for
 goals which can be proven. This would allow for overlapping impls with potentially different

src/traits/specialization.md

@@ -5,7 +5,7 @@
 Defined in the `specialize` module.
 
 The basic strategy is to build up a *specialization graph* during
-coherence checking (coherence checking looks for [overlapping impls](./overlap.md)). 
+coherence checking (coherence checking looks for [overlapping impls](../coherence.md)). 
 Insertion into the graph locates the right place
 to put an impl in the specialization hierarchy; if there is no right
 place (due to partial overlap but no containment), you get an overlap