Add Documentation to LedPulser2.db

@f.feldbauer , a header with basic information and the list of the macros has been added to LedPulser2.db.

The date mentioned in the header originates from the date of the last commit for LedPulser2.db at https://jollyj.ep1.rub.de/dcs/epicsdb.

Closes #2 (closed)