Confirm behaviour for java.home setting

[TrevCraw]

Investigate if we support the java.home setting as described in the VS Code Settings:

It is defined in package.json here:

liberty-tools-vscode/package.json

Lines 214 to 219 in 29ecc9a

	"liberty.terminal.useJavaHome": {
	"type": "boolean",
	"default": false,
	"description": "If this value is true, and if the setting java.home has a value, then the environment variable JAVA_HOME will be set to the value of java.home when a new terminal window is created.",
	"scope": "window"
	}

If we do, we should add documentation for this in the user guide.

Related to #188.