[swift5][client] deprecate Swift 5 generator

Author: 4brunu

docs/generators.md

@@ -68,7 +68,7 @@ The following generators are available:
 * [scala-sttp4-jsoniter (beta)](generators/scala-sttp4-jsoniter.md)  
 * [scalaz](generators/scalaz.md)  
 * [swift-combine](generators/swift-combine.md)  
-* [swift5](generators/swift5.md)  
+* [swift5 (deprecated)](generators/swift5.md)  
 * [swift6](generators/swift6.md)  
 * [typescript (experimental)](generators/typescript.md)  
 * [typescript-angular](generators/typescript-angular.md)