Makefile: clean: remove generated html files

Reviewed-by: Sebastian Spaeth <Sebastian@SSpaeth.de>
Signed-off-by: Nicolas Sebrecht <nicolas.s-dev@laposte.net>

Changelog.draft.rst

@@ -19,6 +19,8 @@ Changes
 Bug Fixes
 ---------
 
+* Makefile: clean removes HTML files
+
 
 Pending for the next major release
 ==================================

Makefile

@@ -34,9 +34,9 @@ clean:
 	-find . -name '*.pygc' -exec rm -f {} \;
 	-find . -name '*.class' -exec rm -f {} \;
 	-find . -name '.cache*' -exec rm -f {} \;
+	-find . -name '*.html' -exec rm -f {} \;
 	-rm -f manpage.links manpage.refs
 	-find . -name auth -exec rm -vf {}/password {}/username \;
-	-rm -f readme.html
 	@$(MAKE) -C docs clean
 
 man: