Update runtime files. Convert a couple of help files to utf-8.
diff --git a/runtime/indent/html.vim b/runtime/indent/html.vim
index b105dca..eb00ea9 100644
--- a/runtime/indent/html.vim
+++ b/runtime/indent/html.vim
@@ -2,7 +2,7 @@
 " Header: "{{{
 " Maintainer:	Bram Moolenaar
 " Original Author: Andy Wokula <anwoku@yahoo.de>
-" Last Change:	2018 Mar 09
+" Last Change:	2018 Mar 12
 " Version:	1.0
 " Description:	HTML indent script with cached state for faster indenting on a
 "		range of lines.
@@ -233,9 +233,9 @@
 call s:AddITags(s:indent_tags, [
     \ 'area', 'article', 'aside', 'audio', 'bdi', 'canvas',
     \ 'command', 'data', 'datalist', 'details', 'embed', 'figcaption',
-    \ 'figure', 'footer', 'header', 'keygen', 'mark', 'meter', 'nav', 'output',
-    \ 'progress', 'rp', 'rt', 'ruby', 'section', 'source', 'summary', 'svg', 
-    \ 'time', 'track', 'video', 'wbr'])
+    \ 'figure', 'footer', 'header', 'keygen', 'main', 'mark', 'meter',
+    \ 'nav', 'output', 'progress', 'rp', 'rt', 'ruby', 'section', 'source',
+    \ 'summary', 'svg', 'time', 'track', 'video', 'wbr'])
 
 " Tags added for web components:
 call s:AddITags(s:indent_tags, [