Specify code listing language as Swift

Author: amartini51

TSPL.docc/LanguageGuide/Concurrency.md

@@ -630,7 +630,7 @@ For a task group that returns a result,
 you add code that accumulates its result
 inside the closure you pass to `withTaskGroup(of:returning:body:)`.
 
-```
+```swift
 let photos = await withTaskGroup(of: Data.self) { group in
     let photoNames = await listPhotos(inGallery: "Summer Vacation")
     for name in photoNames {
@@ -708,7 +708,7 @@ like closing network connections and deleting temporary files.
 [`Task.checkCancellation()`]: https://developer.apple.com/documentation/swift/task/3814826-checkcancellation
 [`Task.isCancelled` type]: https://developer.apple.com/documentation/swift/task/iscancelled-swift.type.property
 
-```
+```swift
 let photos = await withTaskGroup(of: Optional<Data>.self) { group in
     let photoNames = await listPhotos(inGallery: "Summer Vacation")
     for name in photoNames {

TSPL.docc/LanguageGuide/Macros.md

@@ -240,7 +240,7 @@ to add conformance to the `OptionSet` protocol.
 For a freestanding macro,
 you write the `@freestanding` attribute to specify its role:
 
-```
+```swift
 @freestanding(expression)
 public macro line<T: ExpressibleByIntegerLiteral>() -> T =
         /* ... location of the macro implementation... */
@@ -317,7 +317,7 @@ Specifically, Swift expands macros in the following way:
 
 To go through the specific steps, consider the following:
 
-```
+```swift
 let magicNumber = #fourCharacterCode("ABCD")
 ```
 
@@ -413,7 +413,7 @@ That produces a final AST that can be compiled as usual:
 
 This AST corresponds to Swift code like this:
 
-```
+```swift
 let magicNumber = 1145258561 as UInt32
 ```
 

TSPL.docc/ReferenceManual/Expressions.md

@@ -1528,7 +1528,7 @@ However, when a default value is a larger expression
 that contains a macro in addition to other code,
 those macros are evaluated where they appear in the function definition.
 
-```
+```swift
 func f(a: Int = #line, b: Int = (#line), c: Int = 100 + #line) {
     print(a, b, c)
 }