ABNF parsing doesn't work

[AaronLasseigne]

Describe the bug
Parsing ABNF files does not work.

To reproduce
The following uses the latest version of the library and opens examples/abnf/examples/postal-address.abnf from this repo.

> pry
[1] pry(main)> require 'ebnf'
=> true
[2] pry(main)> grammar = EBNF.parse(File.open('postal-address.abnf', format: :abnf))
SyntaxError: ERROR [line: 1] syntax error, expecting "@terminals", "@pass", :LHS (found "postal-address   = n")
from /Users/aaronlasseigne/.asdf/installs/ruby/3.1.0/lib/ruby/gems/3.1.0/gems/ebnf-2.3.0/lib/ebnf/parser.rb:302:in `rescue in initialize'
Caused by EBNF::PEG::Parser::Error: ERROR [line: 1] syntax error, expecting "@terminals", "@pass", :LHS (found "postal-address   = n")
from /Users/aaronlasseigne/.asdf/installs/ruby/3.1.0/lib/ruby/gems/3.1.0/gems/ebnf-2.3.0/lib/ebnf/peg/parser.rb:253:in `parse'

Expected behavior
Parsing ABNF files works.

[AaronLasseigne]

I just noticed the example in the README is wrong. See: https://github.com/dryruby/ebnf#parsing-an-abnf-grammar

- grammar = EBNF.parse(File.open('./etc/abnf.abnf', format: :abnf))
+ grammar = EBNF.parse(File.open('./etc/abnf.abnf'), format: :abnf)

It works as expected. Looks like the README just needs a tweak.