update docs

runtime/doc/if_lua.txt

@@ -207,7 +207,6 @@ Vim evaluation and command execution, and others.
 	vim.fn			Proxy to call Vim functions. Proxy methods are
 				created on demand.  Example: >
 					:lua print(vim.fn.has('timers'))
-					:lua vim.fn.timer_start(1000, function (timer) print('timer callback') end)
 <
 
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@@ -334,6 +333,16 @@ Examples:
 	:lua l = d.len -- assign d as 'self'
 	:lua print(l())
 <
+Lua functions and closures are automatically converted to a vim funcref and
+can be accessed in Vim scripts.
+
+Examples:
+>
+	lua <<EOF
+	vim.fn.timer_start(1000, function(timer)
+	    print('timer callback')
+	end)
+	EOF
 
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 7. Buffer userdata					*lua-buffer*