Update nav header on docs.scala-lang on major bump

Author: Philippus

.github/ISSUE_TEMPLATE/release.md

@@ -119,6 +119,6 @@ Key links:
 - [ ] Create PR to update `versions.properties` (new file generated by the bootstrap job) and the `baseVersion` in `build.sbt` and the MiMa base version and exclusion filters and (if it's a major bump) `spec/_config.yml`
 - If it's a major bump:
   - [ ] PR an update to `latestSpecVersion` in `spec/_config.yml` on the old branch, so that spec is marked as no longer current
-  - [ ] Ditto for the spec link in `_data/footer.yml` on docs.scala-lang.org
+  - [ ] Ditto for the nightly build and spec links in `_data/footer.yml` and `_data/doc-nav-header.yml` on docs.scala-lang.org
 - [ ] Create PR to update https://github.com/lightbend/reactive-platform-docs/blob/master/src/main/paradox/supported-modules/index.md
 - [ ] Update [WhiteSource](https://github.com/lightbend/scala-team/wiki/Whitesource)