Merge pull request #1916 from RazvanN7/patch-2

Update traits.dd
merged-on-behalf-of: Andrei Alexandrescu <andralex@users.noreply.github.com>

Author: dlang-bot

spec/traits.dd

@@ -22,6 +22,7 @@ $(GNAME TraitsKeyword):
     $(GBLINK isFinalClass)
     $(GBLINK isPOD)
     $(GBLINK isNested)
+    $(GBLINK isFuture)
     $(GBLINK isFloating)
     $(GBLINK isIntegral)
     $(GBLINK isScalar)
@@ -192,6 +193,12 @@ $(H2 $(GNAME isNested))
     $(DDSUBLINK spec/struct, nested, structs), and
     $(DDSUBLINK spec/function, variadicnested, functions).)
 
+$(H2 $(GNAME isFuture))
+
+    $(P Takes one argument. It returns `true` if the argument is a symbol
+    marked with the `@future` keyword, otherwise `false`. Currently, only
+    functions and variable declarations have support for the `@future` keyword.)
+
 $(H2 $(GNAME isVirtualFunction))
 
 	$(P The same as $(GLINK isVirtualMethod), except