improve editorUnnecessaryCode.opacity description (for Microsoft/vscode-docs#2264)

src/vs/editor/common/view/editorColorRegistry.ts

@@ -49,8 +49,8 @@ export const editorInfoBorder = registerColor('editorInfo.border', { dark: null,
 export const editorHintForeground = registerColor('editorHint.foreground', { dark: Color.fromHex('#eeeeee').transparent(0.7), light: '#6c6c6c', hc: null }, nls.localize('hintForeground', 'Foreground color of hint squigglies in the editor.'));
 export const editorHintBorder = registerColor('editorHint.border', { dark: null, light: null, hc: Color.fromHex('#eeeeee').transparent(0.8) }, nls.localize('hintBorder', 'Border color of hint squigglies in the editor.'));
 
-export const editorUnnecessaryCodeBorder = registerColor('editorUnnecessaryCode.border', { dark: null, light: null, hc: Color.fromHex('#fff').transparent(0.8) }, nls.localize('unnecessaryCodeBorder', 'Border of unnecessary code in the editor.'));
-export const editorUnnecessaryCodeOpacity = registerColor('editorUnnecessaryCode.opacity', { dark: Color.fromHex('#000a'), light: Color.fromHex('#0007'), hc: null }, nls.localize('unnecessaryCodeOpacity', 'Opacity of unnecessary code in the editor.'));
+export const editorUnnecessaryCodeBorder = registerColor('editorUnnecessaryCode.border', { dark: null, light: null, hc: Color.fromHex('#fff').transparent(0.8) }, nls.localize('unnecessaryCodeBorder', 'Border color of unnecessary (unused) source code in the editor.'));
+export const editorUnnecessaryCodeOpacity = registerColor('editorUnnecessaryCode.opacity', { dark: Color.fromHex('#000a'), light: Color.fromHex('#0007'), hc: null }, nls.localize('unnecessaryCodeOpacity', 'Opacity of unnecessary (unused) source code in the editor. For example, "#000000c0" will render the code with 75% opacity. For high contrast themes, use the  \'editorUnnecessaryCode.border\' theme color to underline unnecessary code instead of fading it out.'));
 
 const rulerRangeDefault = new Color(new RGBA(0, 122, 204, 0.6));
 export const overviewRulerRangeHighlight = registerColor('editorOverviewRuler.rangeHighlightForeground', { dark: rulerRangeDefault, light: rulerRangeDefault, hc: rulerRangeDefault }, nls.localize('overviewRulerRangeHighlight', 'Overview ruler marker color for range highlights. The color must not be opaque to not hide underlying decorations.'), true);