Add releasing instructions

Author: 2m

.travis.yml

@@ -5,8 +5,10 @@ scala: 2.12.4
 jobs:
   include:
     - stage: test
-      script: sbt test
-    - script: sbt scalafmtCheck scalafmtSbtCheck
+      script: sbt scalafmtCheck scalafmtSbtCheck
+      name: "Formatting check"
+    - script: sbt test
+      name: "Tests run"
     - stage: publish
       script: sbt ^publish
 

RELEASING.md

@@ -0,0 +1,10 @@
+# Releasing
+
+1. Check [closed issues without a milestone](https://github.com/lightbend/sbt-paradox-apidoc/issues?utf8=%E2%9C%93&q=is%3Aissue%20is%3Aclosed%20no%3Amilestone) and either assign them the upcoming release milestone or 'invalid'
+1. Create a [new release](https://github.com/lightbend/sbt-paradox-apidoc/releases/new) with:
+    * the next tag version (e.g. `v0.2`)
+    * title and release description including notable changes
+    * link to the [milestone](https://github.com/lightbend/sbt-paradox-apidoc/milestones) showing an overview of closed issues for this release
+    * overview of contributors generated by [`sbt-authors`](https://github.com/2m/authors) (eg. `sbt authors v0.1 v0.2`)
+1. Travis CI will start a [CI build](https://travis-ci.org/lightbend/sbt-paradox-apidoc/builds) for the new tag and publish artifacts to Bintray.
+1. Close the milestone for this release and start a new one.