feat(v2): docs version banner configuration option (#5052)

* refactor DocVersionBanner => versionMetadata prop should be forwarded instead of using "useActiveVersion" + global data

* docs version banner configuration

* add doc for versions.banner

* fix tests

* improve docs plugin option api doc

website/docs/api/plugins/plugin-content-docs.md

@@ -145,14 +145,14 @@ module.exports = {
         /**
          * By default, versioning is enabled on versioned sites.
          * This is a way to explicitly disable the versioning feature.
+         * This will only include the "current" version (the `/docs` directory)
          */
         disableVersioning: false,
         /**
-         * Skip the next release docs when versioning is enabled.
-         * This will not generate HTML files in the production build for documents
-         * in `/docs/next` directory, only versioned docs.
+         * Include the "current" version of your docs (the `/docs` directory)
+         * Tip: turn it off if the current version is a work-in-progress, not ready to be published
          */
-        excludeNextVersionDocs: false,
+        includeCurrentVersion: true,
         /**
          * The last version is the one we navigate to in priority on versioned sites
          * It is the one displayed by default in docs navbar items
@@ -164,8 +164,10 @@ module.exports = {
         lastVersion: undefined,
         /**
          * The docusaurus versioning defaults don't make sense for all projects
-         * This gives the ability customize the label and path of each version
-         * You may not like that default version
+         * This gives the ability customize the properties of each version independantly
+         * - label: the label of the version
+         * - path: the route path of the version
+         * - banner: the banner to show at the top of a doc of that version: "none" | "unreleased" | "unmaintained"
          */
         versions: {
           /*
@@ -173,10 +175,12 @@ module.exports = {
           current: {
             label: 'Android SDK v2.0.0 (WIP)',
             path: 'android-2.0.0',
+            banner: 'none',
           },
           '1.0.0': {
             label: 'Android SDK v1.0.0',
             path: 'android-1.0.0',
+            banner: 'unmaintained',
           },
           */
         },