Merge pull request #459 from dblock/jdk-compatibility

Documented JDK compatibility for version 1.3.0.

_opensearch/install/compatibility.md

@@ -8,14 +8,12 @@ nav_order: 2
 # Operating system and JVM compatibility
 
 - We recommend installing OpenSearch on RHEL- or Debian-based Linux distributions that use [systemd](https://en.wikipedia.org/wiki/Systemd), such as CentOS, Amazon Linux 2, and Ubuntu (LTS). OpenSearch should work on many Linux distributions, but we only test a handful.
-- The OpenSearch tarball ships with a compatible version of Java in the `jdk` directory. To find its version, run `./jdk/bin/java -version`. For example, the OpenSearch 1.0.0 tarball ships with Java 15 (non-LTS).
+- The OpenSearch tarball ships with a compatible version of Java in the `jdk` directory. To find its version, run `./jdk/bin/java -version`. For example, the OpenSearch 1.0.0 tarball ships with Java 15.0.1+9 (non-LTS), while OpenSearch 1.3.0 includes Java 11.0.14.1+1 (LTS).
+- OpenSearch 1.0 to 1.2.4 is built and tested with Java 15, while OpenSearch 1.3.0 is built and tested with Java 8, 11 and 14.
 
-{% comment %}`./jdk/bin/java -version` doesn't work on macOS with zsh at the moment, and I have no idea why. Maybe we need a macOS artifact. Regardless, the command works on Amazon Linux 2 with bash and presumably other distros. - aetter{% endcomment %}
-
-  To use a different Java installation, set the `JAVA_HOME` environment variable to the Java install location. We recommend Java 11 (LTS), but OpenSearch also works with Java 8.
+  To use a different Java installation, set the `OPENSEARCH_JAVA_HOME` or `JAVA_HOME` environment variable to the Java install location. We recommend Java 11 (LTS), but OpenSearch also works with Java 8.
 
 OpenSearch version | Compatible Java versions | Recommended operating systems
 :--- | :--- | :---
-1.x | 8, 11, 15 | Red Hat Enterprise Linux 7, 8; CentOS 7, 8; Amazon Linux 2; Ubuntu 16.04, 18.04, 20.04
-
-If you plan on running applications besides OpenSearch with different Java requirements, set the `OPENSEARCH_JAVA_HOME` environment variable to the location of the Java installation to be used by OpenSearch. `OPENSEARCH_JAVA_HOME` supersedes the `JAVA_HOME` environment variable.
+1.0 - 1.2.x | 11, 15 | Red Hat Enterprise Linux 7, 8; CentOS 7, 8; Amazon Linux 2; Ubuntu 16.04, 18.04, 20.04
+1.3.x | 8, 11, 14 | Red Hat Enterprise Linux 7, 8; CentOS 7, 8; Amazon Linux 2; Ubuntu 16.04, 18.04, 20.04