Add back admonitions in JVM Environment Variables topic in OpenShift documentation

In the section "JVM Environment Variables" (adoc module file ref-jvm-environment-variables.adoc), the row for JAVA_OPTS originally included two admonitions (one note, one important). The admonition markup was removed because it caused the content to render poorly in the table.

Once the table rendering is fixed and the rendering of the admonitions is improved, we need to restore the admonition markup.