Update docs for os-healthcheck toolkit layout

infra-run/scripts/bash/os-healthcheck/healthcheck.sh

@@ -0,0 +1,68 @@
+#!/usr/bin/env bash
+set -o errexit
+set -o nounset
+set -o pipefail
+
+section() {
+  printf '\n== %s ==\n' "$1"
+}
+
+run_or_warn() {
+  local description="$1"
+  shift
+
+  if command -v "$1" >/dev/null 2>&1; then
+    "$@" || printf 'WARNING: %s command failed\n' "$description"
+  else
+    printf 'WARNING: %s command not available\n' "$1"
+  fi
+}
+
+top_processes() {
+  local sort_key="$1"
+
+  if command -v ps >/dev/null 2>&1; then
+    ps -eo pid,ppid,comm,%cpu,%mem --sort="$sort_key" | head -n 11
+  else
+    printf 'WARNING: ps command not available\n'
+  fi
+}
+
+section "Host"
+hostname
+uptime
+
+section "OS"
+if [[ -r /etc/os-release ]]; then
+  . /etc/os-release
+  printf '%s\n' "${PRETTY_NAME:-Unknown Linux}"
+else
+  printf 'WARNING: /etc/os-release not readable\n'
+fi
+uname -r
+
+section "CPU Load"
+if [[ -r /proc/loadavg ]]; then
+  awk '{print "1m="$1, "5m="$2, "15m="$3}' /proc/loadavg
+else
+  uptime
+fi
+
+section "Memory"
+run_or_warn "memory usage" free -h
+
+section "Disk"
+run_or_warn "disk usage" df -h -x tmpfs -x devtmpfs
+
+section "Failed systemd Services"
+if command -v systemctl >/dev/null 2>&1; then
+  systemctl --failed --no-pager || true
+else
+  printf 'WARNING: systemctl command not available\n'
+fi
+
+section "Top CPU Processes"
+top_processes "-%cpu"
+
+section "Top Memory Processes"
+top_processes "-%mem"