Remove v3.3 from release notes and add v3.5

Gerrit v3.3 has been released months ago, therefore it
does not belong to the roadmap anymore.

Move the un-implemented features to the other future
releases of 2021 (v3.4 and v3.5).

Change-Id: I4d043fcee927685cf3735a8c7a21f34e86f83fa3
diff --git a/pages/site/roadmap.md b/pages/site/roadmap.md
index 3f47c7d..03f4b0c 100644
--- a/pages/site/roadmap.md
+++ b/pages/site/roadmap.md
@@ -20,31 +20,15 @@
 If someone would like to be involved when a specific topic is tackled, please
 [reach out to the ESC](https://gerrit-documentation.storage.googleapis.com/Documentation/3.1.0/dev-roles.html#steering-committee-member).
 
-## Gerrit 3.3
-Target: Q4 2020
+## Gerrit 3.4
+Target: Q2 2021
 
-* Performance improvements
-  * Replace H2 persistence with other more performant backends
-  * Improve Gerrit performance with mono-repos (tens of GBytes of size)
 * UX
-  * Attention Set (revising assignee and “bolding”)
-  * Increased overview in Change Log
-  * Porting unresolved comments to the latest patchset
-  * Showing comment context (file content or diff) along with comment widget in ChangeLog and
-    Comment Threads tab
+  * CI Results Tab / Frontend plugin
   * Per-label configuration to copy scores onto successfully cherry-picked changes
-* Infrastructure
-  * TypeScript
-  * Content-Security-Policy
-  * Rework diff caches
-  * Clean up project cache to allow to persist it
-  * Persist project cache
-  * Switch language level to Java 11
-* Plugin Development
-  * Bulk interface for PluginDefinedInfos in ChangeAttributeFactory
-  * Allow plugins to provide is: operands
+* Support for race-free zero-downtime pruning of git packed objects
 
-## Upcoming plugin improvements related to Gerrit 3.3
+## Upcoming plugin improvements related to Gerrit 3.4
 * New plugin: Allow group deletion
 * Replication plugin
   * Support for external replication queue
@@ -52,15 +36,25 @@
   * Improve unit testing
   * Make persistent events safely recoverable
   * Prevent pending events from significantly delaying server startup
+  * Distribute tasks to other nodes via a shared filesystem
+* High-availability plugin
+  * Mention HA and setup for multiple primary hosts in Gerrit documentation
+
+## Gerrit 3.5
+Target: Q4 2021
+
+* UX
+  * Composable SubmitRules
+* Switch language level to Java 11
+
+## Upcoming plugin improvements related to Gerrit 3.5
+* Replication plugin
   * Recover events on time basis instead of startup
   * Do not push to the same destination from more than one primary at a time
     (URI locks)
   * Shift the burden of firing pending events onto the specific
     replication threads for each event's remote
-  * Distribute tasks to other nodes via a shared filesystem
-* High-availability plugin
-  * Support for global ref-db
-  * Mention HA and setup for multiple primary hosts in Gerrit documentation
+
 
 ## Upgrades from 2.7 to latest stable release
 * Be able to upgrade a huge site (Qualcomm) from 2.7 to latest stable release
@@ -68,20 +62,12 @@
   * 2.16.x: Improve NoteDb offline migration speed (current timing is 24+ hours for Qualcomm)
   * Improve upgrade speed for specifically slow schemas
 
-## Gerrit 3.4
-Target: Q2 2021
-
-* UX
-  * Composable SubmitRules
-  * CI Results Tab / Frontend plugin
-
 ## Distant future
 * Role-based access control
 * Evaluate other web frameworks as potential replacements for Polymer
 * Rework event infrastructure
 * Pushing of server events into the frontend
 * Protobuf for REST API entities
-* Support for race-free zero-downtime pruning of git packed objects
 * Pluggable authentication backend
 * Quota plugin
   * Simplify the plugin.