Merge pull request #262 from cplusplus/dfn-style

do not make term definitions (`dfn`) bold

Author: ericniebler

execution.bs

@@ -167,6 +167,10 @@ div.hidden h6 {
   margin-block: 0;
   line-height: 0;
 }
+
+dfn {
+  font-weight: normal;
+}
 </style>
 
 # Introduction # {#intro}