let javadoc.io host our Scaladoc

as per discussion on #469

Author: SethTisue

README.md

@@ -10,7 +10,7 @@ The standard Scala XML library. Please file XML issues here, not at https://gith
 
 The decoupling of scala-xml from the Scala compiler and standard library is possible because the compiler desugars XML literals in Scala source code into a set of method calls. Alternative implementations of these calls are welcome! (The calls are unfortunately only defined by the [implementation](https://github.com/scala/scala/blob/2.11.x/src/compiler/scala/tools/nsc/ast/parser/SymbolicXMLBuilder.scala).)
 
-API documentation is available [here](https://scala.github.io/scala-xml/api/1.2.0/scala/xml/).
+API documentation is available [here](https://javadoc.io/doc/org.scala-lang.modules/scala-xml_2.13/).
 
 How to documentation is available in the [wiki](https://github.com/scala/scala-xml/wiki)
 

build.sbt

@@ -117,9 +117,6 @@ lazy val xml = crossProject(JSPlatform, JVMPlatform)
       )
     },
 
-    apiURL := Some(
-      url(s"""https://scala.github.io/scala-xml/api/${"-.*".r.replaceAllIn(version.value, "")}/""")
-    ),
     apiMappings ++= scalaInstance.value.libraryJars.filter { file =>
       file.getName.startsWith("scala-library") && file.getName.endsWith(".jar")
     }.map { libraryJar =>