Add syntax files from upstream vim repository

indent/docbk.vim

@@ -0,0 +1,19 @@
+if !exists('g:polyglot_disabled') || index(g:polyglot_disabled, 'vim') == -1
+  
+" Vim indent file
+" Language:    	    DocBook Documentation Format
+" Previous Maintainer:  Nikolai Weibull <now@bitwi.se>
+" Latest Revision:      2006-04-19
+
+if exists("b:did_indent")
+  finish
+endif
+
+" Same as XML indenting for now.
+runtime! indent/xml.vim
+
+if exists('*XmlIndentGet')
+  setlocal indentexpr=XmlIndentGet(v:lnum,0)
+endif
+
+endif