Update AwsAutoScaling documentation according to EmptyPolicy support (#795)

* Update AwsAutoScaling documentation according to EmptyPolicy support

* Apply Isabelle's comment

src/docs/admin/references/NodeSourceInfrastructureReference.adoc

@@ -362,6 +362,8 @@ However, it implements a different instance management strategy that reduces the
 	2. The nodes share the same networking infrastructure through a common Virtual Private Cloud (VPC).
  The infrastructure supports networking autoconfiguration if no parameter is supplied.
 
+WARNING: The node source using empty policy will not benefit from this latter management strategy. The deployment with empty policy doesn't use the shared instance template and networking configuration.
+
 ===== Pre-Requisites
 
 The configuration of the AWS Autoscaling infrastructure is subjected to several requirements.
@@ -416,7 +418,7 @@ The configuration form exposes the following fields:
 
 	- *defaultVpcId:* This parameter can be filled with the ID of the VPC to use to operate instance operating nodes.
  If specified, this parameter has to refer to an existing VPC in the region and comply with the VPC ID format. 
- If left blank, the connector will trigger networking autoconfiguration.
+ If left blank, the connector will, first, try to get the default VPC ID in the specified region if set, otherwise it will trigger networking autoconfiguration.
 
 	- *defaultSubNetId:* The administrator can define which subnet has to be attached to the the instance supporting nodes.
  If specified, this parameter has to refer to an existing subnet in the region affected to the specified VPC, and has to comply with the subnet ID format.
@@ -428,7 +430,7 @@ WARNING: Please do not trigger networking autoconfiguration if you operate ProAc
 Otherwise, a new and distinct VPC will be used to operate the nodes created by the NodeSource, preventing their communication with the Resource Manager.
 
 	- *defaultSecurityGroup:* This parameter receives the ID of the security group to spawn instances into.
- If this parameter does not meet the requirement regarding the providing the provided VPC and subnet, a new security group will be generated.
+ If this parameter does not meet the requirement regarding the providing the provided VPC and subnet, a new security group will be generated by default and will be re-used if the same deployment scenario will be repeated.
  This parameter is mandatory, and has to comply with the format of the ID of the AWS security groups.
 
 	- *region:* The administrator specifies here the AWS region to allocate the cluster into.

src/docs/admin/references/properties/scheduler.properties

@@ -161,6 +161,9 @@ pa.scheduler.stax.job.cache=5000
 # Size of the cache used to ensure that delayed jobs or tasks are scheduled at the precise date (without skipping seconds)
 pa.scheduler.startat.cache=5000
 
+# Period of the HSQLDB monitoring thread (in seconds)
+pa.scheduler.hsqldb.monitor.period=10
+
 #-------------------------------------------------------
 #----------------   JOBS PROPERTIES   ------------------
 #-------------------------------------------------------