Fix variable name at tcar_printHelp function.
    
    - Previously, tcar_printHelp function was using the
      TCAR_SCRIPT_DIR_MANUALS variable to read the location of man pages.
      This variable is no longer use which prevent tcar_printHelp from
      knowing where to retrieve man pages from. This update corrects this
      issue by renaming the variable name from TCAR_SCRIPT_DIR_MANUALS to
      TCAR_SCRIPT_MANUAL, the name set in the tcar.sh file.