I fixed the following typos:
1. "Professional" to "Pro" in regards to Windows 8.x (Starting with Windows 8, the business edition was called "Pro".)
2. "System Architecture" to "Architectural SKU" (x86 SKUs of Windows work perfectly well on x64 system. Hence, "system architecture" was not intended here. Plus, x64 itself _is_ x86. That's why the rest of the world outside Microsoft calls it "x86-64".)
3. "32-bit" to "x86" and "64-bit" to "x64". (32-bit and 64-bit are vague because they are not restricted to the Intel x86 family; Windows Server traditionally supported Itanium, which is 64-bit. Starting with Windows 8, Microsoft adopted ARM and ARM64, which are 32-bit and 64-bit respectively.)
