Outdated note in the design doc

[Mason Protter]

JuliaSyntax.jl/docs/src/design.md

Line 364 in a6f2d15

 - Infix macros!? `@(x + y)  ==>  (macrocall @+ x y)` (ok, kinda cute and has 

Unfortunately, this seems to no longer be true:

julia> JuliaSyntax.parsestmt(SyntaxNode, "@(a + b)")
ERROR: ParseError:
# Warning @ line 1:2
@(a + b)
#└─────┘ ── parenthesizing macro names is unnecessary
# Error @ line 1:8
@(a + b)
#      └ ── invalid macro name

... Is there something we can do to re-allow this? I really want infix macros.