Improvement/documentation correction

[blhylton]

Fixed minor issue with documentation surrounding composer exec syntax with options.

When calling a binary or script with Composer, to pass command line arguments, you must also pass a blank option (--) to inform Composer to pass the arguments through.

See:

• composer exec --help
• https://getcomposer.org/doc/articles/scripts.md#running-scripts-manually (Not exec, but approaches arguments the same way.

Updated commands table in README.md to be more compatible

For compatibility reasons, the pipe character preceding and following each table row. GitHub's markdown renderer doesn't care, but some editors/parsers could render this incorrectly.

See: https://www.markdownguide.org/extended-syntax/#tables

[blhylton]

I wanted to leave this out of the PR notes, but the primary reason for the table update was to stop my IDE from yelling about malformed Markdown in the README. If this stops this PR from being accepted for whatever reason, I can revert that commit specifically, as the other part is a bit more pressing.