added jdk 21 to system requirements

Author: jennyowen

modules/ROOT/pages/installation/requirements.adoc

@@ -86,12 +86,12 @@ For personal use and software development:
 .Software requirements for personal use and software development
 [options="header"]
 |===
-| Operating System                    | Supported JDK
-| *Debian 11, 12*                     | OpenJDK 17, OracleJDK 17, and ZuluJDK 17
-| *MacOS 11, 12, 13, 14, 15*          | OpenJDK 17, ZuluJDK 17
-| *SuSE Enterprise Desktop 15*        | OpenJDK 17, OracleJDK 17
-| *Ubuntu Desktop 22.04, 24.04*       | OpenJDK 17, OracleJDK 17, and ZuluJDK 17
-| *Windows 10, 11*                        | OracleJDK 17, ZuluJDK 17
+| Operating System               | Supported JDK
+| *Debian 11, 12*                | OpenJDK 17/21, OracleJDK 17/21, and ZuluJDK 17/21
+| *MacOS 13, 14, 15*             | OpenJDK 17/21, ZuluJDK 17/21
+| *SuSE Enterprise Desktop 15*   | OpenJDK 17/21, OracleJDK 17/21
+| *Ubuntu Desktop 22.04, 24.04*  | OpenJDK 17/21, OracleJDK 17/21, and ZuluJDK 17/21
+| *Windows 11*                   | OracleJDK 17/21, ZuluJDK 17/21
 |===
 
 [NOTE]
@@ -105,12 +105,12 @@ For cloud environments, and server-based, on-premise environments:
 [options="header"]
 |===
 | Operating System                                 | Supported JDK
-| *Amazon Linux 2022 AMI, Amazon Linux 2023 AMI*   | Amazon Corretto 17, and OracleJDK 17
-| *CentOS Stream 8, 9*                             | OpenJDK 17, OracleJDK 17, and ZuluJDK 17
-| *Debian 11, 12*                                  | OpenJDK 17, OracleJDK 17, and ZuluJDK 17
-| *Red Hat Enterprise Linux Server 8.10, 9.2, 9.4* | Red Hat OpenJDK 17,  Oracle JDK 17, and ZuluJDK 17
-| *Ubuntu Server 16.04, 18.04, 20.04, 22.04, 24.04*| OpenJDK 17, OracleJDK 17, and ZuluJDK 17
-| *Windows Server 2016, 2019, 2022, 2025*          | OracleJDK 17, ZuluJDK 17
+| *Amazon Linux 2023 AMI*                          | Amazon Corretto 17/21, and OracleJDK 17/21
+| *CentOS Stream 8, 9*                             | OpenJDK 17/21, OracleJDK 17/21, and ZuluJDK 17/21
+| *Debian 11, 12*                                  | OpenJDK 17/21, OracleJDK 17/21, and ZuluJDK 17/21
+| *Red Hat Enterprise Linux Server 8.10, 9.2, 9.4* | Red Hat OpenJDK 17/21,  Oracle JDK 17/21, and ZuluJDK 17/21
+| *Ubuntu Server 22.04, 24.04*                     | OpenJDK 17/21, OracleJDK 17/21, and ZuluJDK 17/21
+| *Windows Server 2022, 2025*                      | OracleJDK 17/21, ZuluJDK 17/21
 |===
 
 [NOTE]