[Halld-tagger] Tagger magnet simulation note.

[Alexander Somov]

Dear tagger friends,

I've updated the tagger magnet simulation note,
GlueX-doc-1368-v3. You can find addition/changes
in the Appendix of this note.

- the fixed-array and microscope counters energy resolutions
   were updated according to the Geant geometry where the
   microscope counters were moved to the modified
   parallel-to-point focal plane.

- Quadrupole magnet field optimization was added.
   The vertical resolution of the microscope counters
   was updated.

Please send your comments.

Cheers,
       Sascha