Add C# interpolation highlits

colors/highlite.vim

@@ -226,7 +226,7 @@ local highlight_groups = {
 
 	--[[ 4.1.6. Edge Cases]]
 	Special        = {bg=NONE,      fg=magenta,    style='bold'},
-	SpecialChar    = 'Character',
+	SpecialChar    = {bg=NONE,      fg=red_light,  style='italic'},
 	SpecialKey     = 'Character',
 	Tag            = 'Underlined',
 	Delimiter      = {bg=NONE,      fg=white,      style=NONE},
@@ -361,6 +361,8 @@ local highlight_groups = {
 	csContextualStatement = 'Conditional',
 	csEndColon   = 'Delimiter',
 	csGeneric    = 'Typedef',
+	csInterpolation = 'Include',
+	csInterpolationDelimiter = 'SpecialChar',
 	csLogicSymbols  = 'Operator',
 	csModifier   = 'Keyword',
 	csNew        = 'Operator',