Changes

Linting: Fix multiple Javadoc Errors / Warnings

While delving into Citizens2, several build warnings derived from CitizensAPI.

This commit addresses these otherwise benign warnings, and includes minor
grammar changes. Documentation style for @param tags is preserved.

It does not reflect changes where the javadoc may no longer accurately portray
the described methods, or the intent behind them.
 (commit: 95c347a)