Fix invalid URLs (#2715)

Author: stzn

visions/approachable-concurrency.md

@@ -158,9 +158,9 @@ The current execution semantics of async functions also impede programmer’s un
 
 Changing the default execution semantics of nonisolated async functions to run wherever they are called better facilitates progressive disclosure of concurrency. This default allows functions to leverage suspension without forcing callers to cross an isolation boundary and imposing data-race safety checks on arguments and results. A lot of basic asynchronous code can be written correctly and efficiently with only the ability to suspend. When an async function needs to always run off of an actor, the API author can still specify that with a new `@execution(concurrent)` annotation on the function. This provides a better default for most cases while still maintaining the ease of specifying that an async function switches off of an actor to run.
 
-Many programmers have internalized the SE-0338 semantics, and making this change several years after SE-0338 was accepted creates an unfortunate intermediate state where it's difficult to understand the semantics of a nonisolated async function without understanding the build settings of the module you're writing code in. We can alleviate some of these consequences with a careful migration design. There are more details about migration in the [automatic migration](#automatic-migration) section of this document, and in the [source compatibility](https://github.com/hborla/swift-evolution/blob/async-function-isolation/proposals/NNNN-async-function-isolation.md#source-compatibility) section of the proposal for this change.
+Many programmers have internalized the SE-0338 semantics, and making this change several years after SE-0338 was accepted creates an unfortunate intermediate state where it's difficult to understand the semantics of a nonisolated async function without understanding the build settings of the module you're writing code in. We can alleviate some of these consequences with a careful migration design. There are more details about migration in the [automatic migration](#automatic-migration) section of this document, and in the [source compatibility](https://github.com/swiftlang/swift-evolution/blob/main/proposals/0461-async-function-isolation.md#source-compatibility) section of the proposal for this change.
 
-This idea has already been pitched on the forums, and you can read the full proposal for it [here](https://github.com/hborla/swift-evolution/blob/async-function-isolation/proposals/NNNN-async-function-isolation.md).
+This idea has already been pitched on the forums, and you can read the full proposal for it [here](https://github.com/swiftlang/swift-evolution/blob/main/proposals/0461-async-function-isolation.md).
 
 ## Easing incremental migration to data-race safety