It seems the note says:
"seek ye the star of dawn and seek ye too your doom
power beyond all telling
to break the power of the tomb
death to the sorcerer who stole it
for yea he did steal my life
the star that brings power and riches
courts misery, danger, and strife"
This "star of dawn" sounds cursed.
Dorgath takes the gold for splitting later and searches the rest of the corridor for traps and other secret doors.