diff --git a/doc/vimwiki.txt b/doc/vimwiki.txt
index 6f8d6d4..7dd0083 100644
--- a/doc/vimwiki.txt
+++ b/doc/vimwiki.txt
@@ -822,10 +822,14 @@ Vimwiki file.
 *:Vimwiki2HTMLBrowse*
     Convert current wiki page to HTML and open it in the webbrowser.
 
-*:VimwikiAll2HTML*
+*:VimwikiAll2HTML[!]*
     Convert all wiki pages to HTML.
     Default CSS file (style.css) is created if there is no one.
 
+    By default, only converts wiki pages which have not already been
+    converted or have been modified since their last conversion. With !,
+    convert all pages, regardless of whether or not they are out-of-date.
+
 *:VimwikiToggleListItem*
     Toggle checkbox of a list item on/off.
     See |vimwiki-todo-lists|.