fix grammar-o

Juerd++

docs/announce/2015.12.md

@@ -13,7 +13,7 @@ Together, we've built a language that:
 + Retains the core values of Perl: expressiveness, getting the job done,
   taking influences from natural language, and pushing the boundaries of
   language design
-+ Has clean, modern, syntax, rooted in familiar constructs but revisiting
++ Has clean, modern syntax, rooted in familiar constructs but revisiting
   and revising the things that needed it
 + Is truly multi-paradigm, enabling elegant object-oriented, functional,
   procedural, and concurrent programming