add steampipe cli ecit codes to cli reference

[johnsmyth]

add steampipe cli exit codes to cli reference:

const (
    ExitCodeSuccessful                 = 0
    ExitCodeControlsAlarm              = 1   // check - no runtime errors, 1 or more control alarms, no control errors
    ExitCodeControlsError              = 2   // check - no runtime errors, 1 or more control errors
    ExitCodePluginLoadingError         = 11  // plugin - loading error
    ExitCodePluginListFailure          = 12  // plugin - listing failed
    ExitCodePluginNotFound             = 13  // plugin - not found
    ExitCodeSnapshotCreationFailed     = 21  // snapshot - creation failed
    ExitCodeSnapshotUploadFailed       = 22  // snapshot - upload failed
    ExitCodeServiceSetupFailure        = 31  // service - setup failed
    ExitCodeServiceStartupFailure      = 32  // service - start failed
    ExitCodeServiceStopFailure         = 33  // service - stop failed
    ExitCodeQueryExecutionFailed       = 41  // query - 1 or more queries failed - change in behavior(previously the exitCode used to be the number of queries that failed)
    ExitCodeLoginCloudConnectionFailed = 51  // login - connecting to cloud failed
    ExitCodeInitializationFailed       = 250 // common - initialization failed
    ExitCodeBindPortUnavailable        = 251 // common (service/dashboard) - port binding failed
    ExitCodeNoModFile                  = 252 // common - no mod file
    ExitCodeFileSystemAccessFailure    = 253 // common - file system access failed
    ExitCodeInsufficientOrWrongInputs  = 254 // common - runtime error (insufficient or wrong input)
    ExitCodeUnknownErrorPanic          = 255 // common - runtime error (unknown panic)
)

[johnsmyth]

closed in #131