Improve render scale help text in F11 menu (#269)

## Link to GitHub Issue, if one exists
n/a

## Description of change
Previously, F11 menu just provided text-based hint on how to enable
-windowscale option.

Instead, show a disabled checkbox that correctly reflects the current
state, nudging the user to read the tooltip.

Elaborate the option tooltip for -windowscale as well for consistency &
explain *why* you might want to enable this.

## Compiling
💯 

## Testing
Tested 32/64 bit.

src/spice2x/launcher/options.cpp

@@ -1721,7 +1721,7 @@ static const std::vector<OptionDefinition> OPTION_DEFINITIONS = {
         .title = "Window Forced Render Scaling",
         .name = "windowscale",
         .desc = "For windowed mode: forcibly set DX9 back buffer dimensions to match window size. "
-            "Works great on some games, but completely broken on others.",
+            "Reduces pixelated scaling artifacts. Works great on some games, but completely broken on others",
         .type = OptionType::Bool,
         .category = "Graphics (Windowed)",
     },