allows macros to access documentation comments

compiler/vm.nim

@@ -1190,6 +1190,7 @@ proc rawExecute(c: PCtx, start: int, tos: PStackFrame): TFullReg =
       createStr regs[ra]
       let a = regs[rb].node
       if a.kind in {nkStrLit..nkTripleStrLit}: regs[ra].node.strVal = a.strVal
+      elif a.kind == nkCommentStmt: regs[ra].node.strVal = a.comment
       else: stackTrace(c, tos, pc, errFieldXNotFound, "strVal")
     of opcSlurp:
       decodeB(rkNode)