[java] Remove java language version 20-preview

docs/pages/pmd/languages/java.md

@@ -19,7 +19,6 @@ Usually the latest non-preview Java Version is the default version.
 | 22 (default) |       | 7.0.0                  |
 | 21-preview   |       | 7.0.0                  |
 | 21           |       | 7.0.0                  |
-| 20-preview   |       | 6.55.0                 |
 | 20           |       | 6.55.0                 |
 | 19           |       | 6.48.0                 |
 | 18           |       | 6.44.0                 |

docs/pages/release_notes.md

@@ -232,6 +232,10 @@ The rules have been moved into categories with PMD 6.
 
 #### API Changes
 
+**pmd-java**
+
+* Support for Java 20 preview language features have been removed. The version "20-preview" is no longer available.
+
 **New API**
 
 The API around {%jdoc core::util.treeexport.TreeRenderer %} has been declared as stable. It was previously