Corrections and update for Hungarian translation

Minor corrections for the Hungarian translation (spelling, style).
Language file is updated to the latest version (new ACF5 UI strings
added).
Updated .POT catalog

Language catalog .pot file is updated, including new and/or modified UI
strings from latest commits.
Corrected plugin description

Corrected one spelling mistake in the plugin description. This has been
already fixed for ACF4, but still present in ACF5 beta.