Add ARM64 (Sysmon64a.exe) binary coverage to Windows install chapter

[einlamye]

Microsoft's Sysmon download now ships three command-line binaries, not two. The Windows
install chapter only documented Sysmon.exe and Sysmon64.exe, omitting the ARM64 build
Sysmon64a.exe. This updates the chapter so ARM64 Windows hosts are covered.

Changes

• chapters/install_windows.md
  • "two command line versions" → "three", and added a **Sysmon64a.exe** - ARM64 (64-bit ARM) version. bullet.
  • Added a dedicated "ARM64 Process" subsection (matching the existing "Process for x86" and "x64 Process" sections): explains Sysmon64a.exe is the native ARM64 build for Windows on ARM (Snapdragon PCs, Surface Pro X, ARM64 VMs), why the native binary is required (the SysmonDrv kernel driver must match the OS architecture and cannot load under x64 emulation), that the install flow/driver/service/event-log/config schema are otherwise identical to x64, and a Sysmon64a.exe -i --accepteula -c <config> example.
  • Main-service Name note: (default Sysmon or Sysmon64) → (default Sysmon, Sysmon64, or Sysmon64a).
  • Best-practice WMI version filter now also matches c:\Windows\Sysmon64a.exe.