Mark as generated

Author: StanFromIreland

.gitattributes

@@ -68,6 +68,7 @@ PCbuild/readme.txt  dos
 **/clinic/*.cpp.h                                   generated
 **/clinic/*.h.h                                     generated
 *_db.h                                              generated
+Doc/_static/tachyon-example-*.html                  generated
 Doc/c-api/lifecycle.dot.svg                         generated
 Doc/data/stable_abi.dat                             generated
 Doc/library/token-list.inc                          generated