jsoncpp: Drop doxygen comments not recognized by Clang

Some Clang versions warn with `-Wdocumentation-unknown-command` about
the `\internal` and `\snippet` command tag names.

Utilities/cmjsoncpp/include/json/writer.h

@@ -135,7 +135,7 @@ public:
   /** Called by ctor, but you can use this to reset settings_.
    * \pre 'settings' != NULL (but Json::null is fine)
    * \remark Defaults:
-   * \snippet src/lib_json/json_writer.cpp StreamWriterBuilderDefaults
+   * snippet src/lib_json/json_writer.cpp StreamWriterBuilderDefaults
    */
   static void setDefaults(Json::Value* settings);
 };