Fixed the Gradle Tooling versioning nimber for 12.0

The Gradle Tooling API on 12.0 is 6.3. It is just for the correctness of the page.
diff --git a/netbeans.apache.org/src/content/download/nb120/index.asciidoc b/netbeans.apache.org/src/content/download/nb120/index.asciidoc
index 5838b1c..a52ac6e 100644
--- a/netbeans.apache.org/src/content/download/nb120/index.asciidoc
+++ b/netbeans.apache.org/src/content/download/nb120/index.asciidoc
@@ -232,7 +232,7 @@
 
 TIP: Currently, Apache NetBeans supports Java EE, though not yet Jakarta EE. The Jakarta EE APIs are identical to Java EE 8, though there are new JARs that are now packaged under the Eclipse Foundation and all APIs have been slightly renamed. 
 
-However, there are multiple other new features, enhancements, and fixes for Gradle users, which together provide comprehensive Gradle tooling for the first time and fills in multiple gaps. These include upgraded Gradle Tooling API to 6.0, new Java Frontend Application wizard for Gradle, debugger support for Gradle Web projects, support for custom Gradle Home, support for composite projects, Kotlin-based Gradle projects, and forceable reloading of Gradle projects.
+However, there are multiple other new features, enhancements, and fixes for Gradle users, which together provide comprehensive Gradle tooling for the first time and fills in multiple gaps. These include upgraded Gradle Tooling API to 6.3, new Java Frontend Application wizard for Gradle, debugger support for Gradle Web projects, support for custom Gradle Home, support for composite projects, Kotlin-based Gradle projects, and forceable reloading of Gradle projects.
 
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