Remove option 2 of 'auto_toc'

It doesn't really work for :VimwikiAll2HTML

autoload/vimwiki/html.vim

@@ -1328,11 +1328,6 @@ endfunction " }}}
 
 function! vimwiki#html#Wiki2HTML(path_html, wikifile) "{{{
 
-  if VimwikiGet('auto_toc') >= 1
-    call vimwiki#base#table_of_contents(0)
-    noautocmd update
-  endif
-
   let starttime = reltime()  " start the clock
 
   let done = 0

doc/vimwiki.txt

@@ -1740,17 +1740,14 @@ This will keep your HTML files up to date.
 
 *vimwiki-option-auto_toc*
 ------------------------------------------------------------------------------
-Set this option to a value greater than 0 to automatically update the Table of
-Contents: >
+Key             Default value     Values~
+auto_toc        0                 0, 1
+
+Description~
+Set this option to 1 to automatically generate the table of contents when the
+current wiki page is saved: >
   let g:vimwiki_list = [{'path': '~/my_site/', 'auto_toc': 1}]
 
-Value           Description~
-0               Don't update it automatically.
-1               Update when the wiki file is converted to HTML.
-2               Update when the wiki file is saved.
-
-Default: 0
-
 
 *vimwiki-option-index*
 ------------------------------------------------------------------------------

ftplugin/vimwiki.vim

@@ -617,7 +617,7 @@ nnoremap <silent><buffer> <Plug>VimwikiRemoveHeaderLevel :
 
 " AUTOCOMMANDS {{{
 function! s:toc_html()
-  if VimwikiGet('auto_toc') >= 2 && VimwikiGet('auto_export') == 0
+  if VimwikiGet('auto_toc')
     call vimwiki#base#table_of_contents(0)
   endif
   if VimwikiGet('auto_export')
@@ -626,7 +626,7 @@ function! s:toc_html()
   endif
 endfunction
 
-if VimwikiGet('auto_export') || VimwikiGet('auto_toc') >= 2
+if VimwikiGet('auto_export') || VimwikiGet('auto_toc')
   augroup vimwiki
     au BufWritePost <buffer> call s:toc_html()
   augroup END