doc: clarify build support text

Revise compilation/execution support text to keep it shorter, simpler, and hopefully easier to read/understand.

As someone else said in another PR, squinting may be required to see the difference, but I do think this is easier to read/understand.

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• documentation is changed or added
• commit message follows commit guidelines