Atlanta St, aka SR42 southbound into McDonough

Changing road ID #15110042SO functional class from 4 (Minor arterial) to 3 (Principal arterial).
### Description
2 lane southbound approach into McDonough from the north.  AADT ~5000.
### Justification
Related to request to upgrade SR42 to FC-3 between SR155 and SR42/138.
#### Entire segment
#### County
Henry County