Clean up references to carbon-language#3720 now that it is merged

Author: josh11b

proposals/p3802.md

@@ -86,7 +86,7 @@ This proposal builds upon a number of previous proposals:
 -   [Proposal 2760: Consistent `class` and `interface` syntax](https://github.com/carbon-language/carbon-lang/pull/2760)
     changed the syntax to consistently use the `extend` keyword for any language
     construct that involves delegating name lookup to another type.
--   [Proposal #3720: Binding operators](https://github.com/carbon-language/carbon-lang/pull/3720)
+-   [Proposal #3720: Member binding operators](https://github.com/carbon-language/carbon-lang/pull/3720)
     introduced customization of how member binding works, as in `x.y` or
     `x.(y)`. This proposal was originally part of #3720, but was split out.
 
@@ -229,7 +229,7 @@ This means that lookup into `Box(T)` also looks in the type `T` for members. In
 this way, `b.Search` will find `b.(String.Search)`.
 
 For the second ingredient, the binding interfaces from
-[proposal #3720: "Binding operators"](https://github.com/carbon-language/carbon-lang/pull/3720)
+[proposal #3720: "Member binding operators"](https://github.com/carbon-language/carbon-lang/pull/3720)
 already provide everything needed, we just need to make a parameterized
 implementation of them:
 
@@ -328,12 +328,8 @@ This application of `extend api` and binding was first described in
 
 A class could extend the API of a class it implicitly converts to. For example,
 imagine we have a class representing an integer in a restricted range that can
-implicitly convert to an integer value.
-
-<!--FIXME: add text once #3720 is merged:
-> , see
-> [inheritance and other implicit conversions from proposal #3720](p3720.md#inheritance-and-other-implicit-conversions).
--->
+implicitly convert to an integer value, see
+[inheritance and other implicit conversions from proposal #3720](p3720.md#inheritance-and-other-implicit-conversions).
 
 ```carbon
 class I32InRange(Low:! i32, High:! i32) {
@@ -575,10 +571,8 @@ class D {
 }
 ```
 
-<!--FIXME: add text once #3720 is merged:
 Note that
-[implicit conversions are sufficient for binding to work, no additional binding implementations are needed](p3720.md#inheritance-and-other-implicit-conversions).
--->
+[implicit conversions are sufficient for member binding to work, no additional member binding implementations are needed](p3720.md#inheritance-and-other-implicit-conversions).
 
 **Future work:** Currently the Carbon design doesn't include base-to-derived
 conversions. When they are added, it would be good to also have a way to model
@@ -1138,7 +1132,7 @@ disadvantages:
     preventing cycles (`A` extends `B` extends `C` extends `A`).
 
 This was discussed in the
-[proposal review](https://github.com/carbon-language/carbon-lang/pull/3720/files#r1507988547)
+[proposal review](https://github.com/carbon-language/carbon-lang/pull/3720/files/19774c5013706e5795a7952f0c6f08a73872a036#r1507988547)
 and
 [the #typesystem channel on Discord](https://discord.com/channels/655572317891461132/708431657849585705/1217499991329738852).