[doc] Update release notes, new rule UnusedAssignment

docs/pages/release_notes.md

@@ -14,6 +14,12 @@ This is a {{ site.pmd.release_type }} release.
 
 ### New and noteworthy
 
+#### New Rules
+
+*   The new Java rule {% rule "java/bestpractices/UnusedAssignment" %} (`java-bestpractices`) finds assignments
+    to variables, that are never used and are useless. The new rule is supposed to entirely replace
+    {% rule "java/errorprone/DataflowAnomalyAnalysis" %}.
+
 ### Fixed Issues
 
 ### API Changes

pmd-core/src/main/resources/rulesets/releases/6260.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0"?>
+
+<ruleset name="6260"
+    xmlns="http://pmd.sourceforge.net/ruleset/2.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://pmd.sourceforge.net/ruleset/2.0.0 https://pmd.sourceforge.io/ruleset_2_0_0.xsd">
+  <description>
+This ruleset contains links to rules that are new in PMD v6.26.0
+  </description>
+
+    <rule ref="category/java/bestpractices.xml/UnusedAssignment" />
+
+</ruleset>

pmd-java/src/main/resources/category/java/bestpractices.xml

@@ -1316,7 +1316,8 @@ class Foo{
 
             The rule may be suppressed with the standard `@SuppressWarnings("unused")` tag.
 
-            The rule subsumes UnusedLocalVariable, and UnusedFormalParameter. Those violations are filtered
+            The rule subsumes {% rule "UnusedLocalVariable" %}, and {% rule "UnusedFormalParameter" %}.
+            Those violations are filtered
             out by default, in case you already have enabled those rules, but may be enabled with the property
             `reportUnusedVariables`. Variables whose name starts with `ignored` are filtered out, as
             is standard practice for exceptions.

pmd-java/src/main/resources/rulesets/java/quickstart.xml

@@ -41,6 +41,7 @@
     <!-- <rule ref="category/java/bestpractices.xml/ReplaceVectorWithList" /> -->
     <rule ref="category/java/bestpractices.xml/SwitchStmtsShouldHaveDefault"/>
     <!-- <rule ref="category/java/bestpractices.xml/SystemPrintln" /> -->
+    <!-- <rule ref="category/java/bestpractices.xml/UnusedAssignment"/> -->
     <rule ref="category/java/bestpractices.xml/UnusedFormalParameter"/>
     <rule ref="category/java/bestpractices.xml/UnusedImports"/>
     <rule ref="category/java/bestpractices.xml/UnusedLocalVariable"/>