[lld][WebAssembly] Add a comment on isStatic default

Author: yamt

lld/wasm/Config.h

@@ -72,6 +72,8 @@ struct Configuration {
   bool stripAll;
   bool stripDebug;
   bool stackFirst;
+  // Because dyamanic linking under Wasm is still experimental we default to
+  // static linking
   bool isStatic = true;
   bool trace;
   uint64_t globalBase;