Add configurable social links to scala3doc

Author: pikinier20

project/Build.scala

@@ -1624,6 +1624,9 @@ object Build {
               "-skip-by-regex:.+\\.impl($|\\..+) " +
               "-comment-syntax wiki -siteroot scaladoc/scala3-docs -project-logo scaladoc/scala3-docs/logo.svg " +
               "-external-mappings:.*java.*::javadoc::https://docs.oracle.com/javase/8/docs/api/ " +
+              "-social-links:github::https://github.com/lampepfl/dotty," +
+              "gitter::https://gitter.im/scala/scala," +
+              "twitter::https://twitter.com/scala_lang " +
               s"-source-links:$stdLibRoot=github://scala/scala/v${stdlibVersion(Bootstrapped)}#src/library " +
               s"-doc-root-content $docRootFile"
               ))

scaladoc-js/src/Main.scala

@@ -2,4 +2,5 @@ package dotty.tools.scaladoc
 
 object Main extends App {
   Searchbar()
+  SocialLinks()
 }

scaladoc-js/src/social-links/SocialLinks.scala

@@ -0,0 +1,12 @@
+package dotty.tools.scaladoc
+
+import org.scalajs.dom._
+import org.scalajs.dom.ext._
+
+class SocialLinks:
+  def addIcon(elem: html.Element) =
+    val img = document.createElement("img").asInstanceOf[html.Image]
+    img.src = s"${Globals.pathToRoot}images/${elem.getAttribute("data-icon-path")}"
+    elem.appendChild(img)
+
+  document.querySelectorAll(".social-icon").collect { case e: html.Element => e }.foreach(addIcon)

scaladoc/README.md

@@ -167,3 +167,9 @@ Make sure all the tests pass (simply run `sbt test` to verify that).
 A documentation tool needs to access compiler information about the project - it
 needs to list all definitions, resolve them by name, and query their members.
 Tasty Reflect is the dedicated way in Scala 3 of accessing this information.
+
+## Credits
+
+- [Flatart](https://www.iconfinder.com/Flatart) - Gitter icon
+
+