Add reference for p2505, update table 'Comparison with like types' (#60…

…) [skip-ci]

README.md

@@ -296,7 +296,7 @@ You can use the R3 revision of P2505, which lacks `error_or`, and uses `remove_c
 |                      |             |               |               |                  |                |               |                |               |
 |Proxy (rel.ops)       | no          | yes           | yes           | yes              | yes            | no            | no             | no            |
 |References            | no          | yes           | no/not yet    | no/not yet       | no/not yet     | yes           | no             | no            |
-|Chained visitor(s)    | no          | no            | yes           | maybe            | yes            | no            | no             | no            |
+|Chained visitor(s)    | no          | no            | yes           | yes              | yes            | no            | no             | no            |
 
 Note 1: std::*experimental*::expected
 
@@ -351,6 +351,8 @@ TBD
 
 [16] Niall Douglas. [p0762 - Concerns about expected<T, E> from the Boost.Outcome peer review](http://wg21.link/p0762). 15 October 2017.
 
+[17] Jeff Garland. [p2505 - Monadic Functions for `std::expected`](http://wg21.link/p2505) (HTML). ([r0](http://wg21.link/p2505r0), [r1](http://wg21.link/p2505r1), [r2](http://wg21.link/p2505r2), [r3](http://wg21.link/p2505r3), [r4](http://wg21.link/p2505r4), [r5](http://wg21.link/p2505r5)).
+
 ## Appendix
 
 ### A.1 Compile-time information