Merge pull request #2246 from MadsBogeskov/patch-1

Added missing import

Author: ahoppen

Sources/SwiftSyntax/Documentation.docc/Working with SwiftSyntax.md

@@ -188,6 +188,7 @@ trees when the `SwiftSyntaxBuilder` module is also imported:
 ```
 import SwiftSyntax
 import SwiftParser
+import SwiftSyntaxBuilder
 
 // `file` is a source file syntax node containing the parsed value of the
 // provided text.