Update ddc-file.txt

Author: LumaKernel

doc/ddc-file.txt

@@ -50,6 +50,7 @@ EXAMPLES						   *ddc-file-examples*
 	    \ 'file': {
 	    \   'mark': 'F',
 	    \   'isVolatile': v:true,
+	    \   'minAutoCompleteLength': 1000,
 	    \   'forceCompletionPattern': '\S/\S*',
 	    \ }})
 	call ddc#custom#patch_filetype(