Update jdk tag to java 21 of mc 1.20.5 (#157)

* Add JDK 21 for mc 1.20.5 or later

* Apply suggestions from code review

Co-authored-by: Kevin <92656833+kevinthegreat1@users.noreply.github.com>

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Co-authored-by: Kevin <92656833+kevinthegreat1@users.noreply.github.com>

tags/link/jdk.ytag

@@ -6,5 +6,6 @@ embed:
 
 ---
 
-[Java 17](https://adoptium.net/?variant=openjdk17&jvmVariant=hotspot) for Minecraft 1.17 and later
+[Java 21](https://adoptium.net/?variant=openjdk21&jvmVariant=hotspot) for Minecraft 1.20.5 and later
+[Java 17](https://adoptium.net/?variant=openjdk17&jvmVariant=hotspot) for Minecraft 1.17 to 1.20.4
 [Java 8](https://adoptium.net/?variant=openjdk8&jvmVariant=hotspot) for Minecraft 1.16 and earlier