chore: prepare the package for further development

1. Add a new version to pkgdown/versions.yml.
2. Set a development version in DESCRIPTION.
3. Update NEWS.md.

DESCRIPTION

@@ -1,6 +1,6 @@
 Package: rhino
 Title: A Framework for Enterprise Shiny Applications
-Version: 1.9.0
+Version: 1.9.0.9000
 Authors@R:
   c(
     person("Kamil", "Żyła", role = c("aut", "cre"), email = "[email protected]"),

NEWS.md

@@ -1,4 +1,8 @@
-# rhino 1.9.0
+# rhino (development version)
+
+# [rhino 1.9.0](https://github.com/Appsilon/rhino/releases/tag/v1.9.0)
+
+See _[How-to: Rhino 1.9 Migration Guide](https://appsilon.github.io/rhino/articles/how-to/migrate-1-9.html)_
 
 1. Added `sass: custom` configuration option for cleaner integration with `bslib`.
 2. Introduced `format_js()` and `format_sass()` powered by [prettier](https://prettier.io).
@@ -8,11 +12,11 @@
 
 # [rhino 1.8.0](https://github.com/Appsilon/rhino/releases/tag/v1.8.0)
 
+See _[How-to: Rhino 1.8 Migration Guide](https://appsilon.github.io/rhino/articles/how-to/migrate-1-8.html)_
+
 1. All linter functions migrated to `box.linters`. New rhino projects will be configured to use linters from `box.linters`.
 2. Updated GitHub Workflow template triggers.
 
-See _[How-to: Rhino 1.8 Migration Guide](https://appsilon.github.io/rhino/articles/how-to/migrate-1-8.html)_
-
 # [rhino 1.7.0](https://github.com/Appsilon/rhino/releases/tag/v1.7.0)
 
 See _[How-to: Rhino 1.7 Migration Guide](https://appsilon.github.io/rhino/articles/how-to/migrate-1-7.html)_

pkgdown/versions.yml

@@ -1,8 +1,11 @@
 - git_ref: 'refs/remotes/origin/main'
   url: /dev
   label: true
-- git_ref: 'refs/tags/v1.8.0'
+- git_ref: 'refs/tags/v1.9.0'
   url: '/'
+  label: '1.9'
+- git_ref: 'refs/tags/v1.8.0'
+  url: '/v1.8.0'
   label: '1.8'
 - git_ref: 'refs/tags/v1.7.0'
   url: '/v1.7.0'