Documentation: fix a few links

Author: Morwenn

docs/Comparators.md

@@ -117,11 +117,11 @@ The two-parameter version of the customization point calls the three-parameter o
 *Changed in version 1.5.0:* `case_insensitive_less` is an instance of type `case_insensitive_less_t`.
 
 
-  [binary-predicate]: https://en.cppreference.com/w/cpp/concept/BinaryPredicate
+  [binary-predicate]: https://en.cppreference.com/w/cpp/named_req/BinaryPredicate
   [branchless-traits]: Miscellaneous-utilities.md#branchless-traits
   [callable]: https://en.cppreference.com/w/cpp/named_req/Callable
   [case-sensitivity]: https://en.wikipedia.org/wiki/Case_sensitivity
-  [cppcon2015-compare]: https://github.com/CppCon/CppCon2015/tree/master/Presentations/Comparison%20is%20not%20simple%2C%20but%20it%20can%20be%20simpler%20-%20Lawrence%20Crowl%20-%20CppCon%202015
+  [cppcon2015-compare]: https://github.com/CppCon/CppCon2015/tree/master/Presentations/Comparison%20is%20not%20simple%2C%20but%20it%20can%20be%20simpler
   [custom-point]: https://ericniebler.com/2014/10/21/customization-point-design-in-c11-and-beyond/
   [natural-sort]: https://en.wikipedia.org/wiki/Natural_sort_order
   [P0100]: http://open-std.org/JTC1/SC22/WG21/docs/papers/2015/p0100r1.html

docs/Original-research.md

@@ -228,7 +228,7 @@ The following relations have yet to be analyzed:
 
   [better-sorting-networks]: https://etd.ohiolink.edu/!etd.send_file?accession=kent1239814529
   [cycle-sort]: https://en.wikipedia.org/wiki/Cycle_sort
-  [divide-sort-merge-strategy]: http://www.dtic.mil/dtic/tr/fulltext/u2/737270.pdf
+  [divide-sort-merge-strategy]: https://apps.dtic.mil/sti/tr/pdf/AD0737270.pdf
   [exact-sort]: https://www.geocities.ws/p356spt/
   [indirect-adapter]: Sorter-adapters.md#indirect_adapter
   [morwenn-gist]: https://gist.github.com/Morwenn