fix(editorconfig): use off instead of 0 for max line length (#3186)

see https://github.com/editorconfig/editorconfig/wiki/EditorConfig-Properties#max_line_length

Author: scttcper

packages/angular-cli/blueprints/ng2/files/.editorconfig

@@ -9,5 +9,5 @@ insert_final_newline = true
 trim_trailing_whitespace = true
 
 [*.md]
-max_line_length = 0
+max_line_length = off
 trim_trailing_whitespace = false