Kotlin: document preliminary 2.4.20-RC support

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: andersfugmann

docs/codeql/reusables/supported-versions-compilers.rst

@@ -21,7 +21,7 @@
    Java,"Java 7 to 26 [5]_","javac (OpenJDK and Oracle JDK),
 
    Eclipse compiler for Java (ECJ) [6]_",``.java``
-   Kotlin,"Kotlin 1.8.0 to 2.4.1\ *x*","kotlinc",``.kt``
+   Kotlin [13]_,"Kotlin 1.8.0 to 2.4.20-RC","kotlinc",``.kt``
    JavaScript,ECMAScript 2022 or lower,Not applicable,"``.js``, ``.jsx``, ``.mjs``, ``.es``, ``.es6``, ``.htm``, ``.html``, ``.xhtm``, ``.xhtml``, ``.vue``, ``.hbs``, ``.ejs``, ``.njk``, ``.json``, ``.yaml``, ``.yml``, ``.raml``, ``.xml`` [7]_"
    Python [8]_,"2.7, 3.5, 3.6, 3.7, 3.8, 3.9, 3.10, 3.11, 3.12, 3.13, 3.14",Not applicable,``.py``
    Ruby,"up to 3.3",Not applicable,"``.rb``, ``.erb``, ``.gemspec``, ``Gemfile``"
@@ -43,3 +43,4 @@
     .. [10] Support for the analysis of Swift requires macOS.
     .. [11] Embedded Swift is not supported.
     .. [12] TypeScript analysis is performed by running the JavaScript extractor with TypeScript enabled. This is the default.
+    .. [13] Support for Kotlin 2.4.20-RC is preliminary.

java/ql/lib/change-notes/2026-08-21-kotlin-2.4.20.md

@@ -0,0 +1,4 @@
+---
+category: minorAnalysis
+---
+* Preliminary support for Kotlin 2.4.20-RC has been added.