Setup publishing for Yoga stables

Summary:
This sets up publishing for stable of Yoga whenever a git tag gets published.
I also re-enabled Javadoc publishing as this is a requirement to hit Maven Central.

Reviewed By: NickGerleman

Differential Revision: D46522898

fbshipit-source-id: dc4b9139aed7aff27dce966bcee7b9b0cc4c6fe9

android/build.gradle

@@ -30,6 +30,7 @@ android {
     publishing {
         multipleVariants {
             withSourcesJar()
+            withJavadocJar()
             includeBuildTypeValues('debug', 'release')
         }
     }
@@ -38,9 +39,3 @@ android {
 dependencies {
     api project(':yoga')
 }
-
-// We don't build Javadoc at this time as we can't disable "BUCK" files
-// from mistakenly getting parsed as Java.
-tasks.withType(Javadoc).all {
-  enabled = false
-}