Add NET_RAW capability requirement for ICMP ping

Agent was crashing with segmentation fault (exit code 139) when
attempting ICMP ping health checks. The surge-ping library requires
CAP_NET_RAW capability to create raw sockets for ICMP.

Changes:
- Added cap_add: NET_RAW to docker-compose.example.yml
- Updated README docker-compose example
- Added troubleshooting section for exit code 139 crashes

Without this capability, the agent crashes immediately after
successful ping execution when the surge-ping library attempts
to clean up raw socket resources.

README.md

@@ -38,6 +38,9 @@ services:
   towerops-agent:
     image: ghcr.io/towerops-app/towerops-agent:latest
     restart: unless-stopped
+    # Required for ICMP ping health checks
+    cap_add:
+      - NET_RAW
     environment:
       - TOWEROPS_API_URL=https://towerops.net
       - TOWEROPS_AGENT_TOKEN=your-agent-token-here
@@ -122,6 +125,17 @@ docker build -t towerops-agent .
 
 ## Troubleshooting
 
+### Agent Crashes with Segmentation Fault (Exit Code 139)
+
+This typically occurs when the container doesn't have the `NET_RAW` capability required for ICMP ping:
+
+```yaml
+cap_add:
+  - NET_RAW
+```
+
+Add this to your `docker-compose.yml` under the agent service. Without this capability, the agent will crash when attempting health checks.
+
 ### Agent Not Connecting
 
 - Verify the API URL is correct (accepts http://, https://, ws://, or wss://)

docker-compose.example.yml

@@ -4,6 +4,10 @@ services:
     container_name: towerops-agent
     restart: unless-stopped
 
+    # Required for ICMP ping health checks
+    cap_add:
+      - NET_RAW
+
     environment:
       # Required: Agent authentication token (from Towerops web UI)
       # Get this from: Organization > Agents > Create New Agent