Update role name for Local Chair and pluralise Advisor

[lucasresck]

This PR introduces two changes:

1. Change the name of the Local Chair to use the one specified by the General Chair: "Local Arrangements Chair" -> "Local Chair". This could have been done directly in the organizers.csv list but it would drop the "special" category of the Local Chair in the website's logic.
2. Pluralise "Advisor" in the "Faculty Advisor to the Student Research Workshop" title. This could have been done in the organisers list file, but this particular role would then have a "Chair" appended to it, which would require an extra fix.

These changes are orthogonal to the first version of the website, simplifying the review.