Many corrections to SHMS/standard.kinematics file

- Added comments for the PolHe3 runs to help with interpretation.

- NOTE: 'gtargmass_amu' was found to be wrong for many of the Pol He3
    Runs.  This was likely due to a missed update of the target ladder
    encoder positions after a target change out.

    - *If* gtargmass_amu is actually used in the code, we should also
      recheck this database against the json run database.
      - I do not think we actually care, but updating anyway, just in case.