PDB: Update type info stream description
PDB: Update type info stream description

BUG=
R=siggi@chromium.org

Review URL: https://codereview.chromium.org/1311043017.

google/syzygy,google/syzygy,google/syzygy,supriyantomaftuh/syzygy,Eloston/syzygy,google/syzygy,supriyantomaftuh/syzygy,supriyantomaftuh/syzygy,supriyantomaftuh/syzygy,Eloston/syzygy