env.example: add jicofo and jvb env vars for defining max memory.

env.example

@@ -36,6 +36,12 @@ TZ=UTC
 # https://jitsi.github.io/handbook/docs/devops-guide/devops-guide-docker#running-behind-nat-or-on-a-lan-environment
 #JVB_ADVERTISE_IPS=192.168.1.1,1.2.3.4
 
+#
+# Memory limits for Java components
+#
+
+#JICOFO_MAX_MEMORY=3072m
+#VIDEOBRIDGE_MAX_MEMORY=3072m
 
 #
 # JaaS Components (beta)