added doc for enabling ebpf

Author: Vipin Kumar

solutions/fully-configurable/DA-docs.md

@@ -0,0 +1,12 @@
+When attempting to deploy the agents to cluster nodes on RH CoreOS that have no public gateways enabled (and/or have outbound traffic disabled), the pods fail to come up with the error:
+```
+Download of sysdigcloud-probe for version 13.9.2 failed.
+curl: (28) Failed to connect to download.sysdig.com port 443: Connection timed out
+Cannot load the probe
+```
+
+This happens because the agent tries to connect to the kernel and for that it needs a kernel module (default behaviour):
+- If not available in the machine already, it tries to build it with the kernel headers
+- if kernel headers not available, it tries to download it
+
+To fix this, we need the ability to set the helm values `agent.ebpf.enabled` and `agent.ebpf.kind` if cluster is using nodes based on RHCOS by setting the terraform boolean input variable called `enable_universal_ebpf` to true. Enabling universal ebpf needs kernel version to be `5.8` or higher. RHEL8 already has the kernel headers and enabling `ebpf` will not cause any impact even though kernel version is `4.18`.

solutions/fully-configurable/variables.tf

@@ -235,6 +235,6 @@ variable "agent_limits_memory" {
 
 variable "enable_universal_ebpf" {
   type        = bool
-  description = "Deploy sysdig agent with universal eBPF enabled. It requires kernel version 5.8+."
+  description = "Deploy sysdig agent with universal eBPF enabled. It requires kernel version 5.8+. [Learn more](https://github.com/terraform-ibm-modules/terraform-ibm-monitoring-agent/tree/main/solutions/fully-configurable/DA-docs.md)."
   default     = true
 }