Tweak the MkDocs build

Retain the 3.x docs by doing a dirty MkDocs build
Build more Dokka projects

okhttp-dnsoverhttps/build.gradle

@@ -16,3 +16,10 @@ dependencies {
   testImplementation deps.junit
   testImplementation deps.assertj
 }
+
+afterEvaluate { project ->
+  project.tasks.dokka {
+    outputDirectory = "$rootDir/docs/api"
+    outputFormat = 'gfm'
+  }
+}